Shrink ObjC overhead (generated size and some runtime sizes)

NOTE: This is a binary breaking change as structure sizes have changed size and/or order. - Drop capturing field options, no other options were captured and other mobile targeted languages don't try to capture this sort information (saved 8 bytes for every field defined (in static data and again in field descriptor instance size data). - No longer generate/compile in the messages/enums in descriptor.proto. If developers need it, they should generate it and compile it in. Reduced the overhead of the core library. - Compute the number of has_bits actually needs to avoid over reserving. - Let the boolean single fields store via a has_bit to avoid storage, makes the common cases of the instance size smaller. - Reorder some flags and down size the enums to contain the bits needed. - Reorder the items in the structures to manually ensure they are are packed better (especially when generating 64bit code - 8 bytes for every field, 16 bytes for every extension, instance sizes 8 bytes also). - Split off the structure initialization so when the default is zero, the generated static storage doesn't need to reserve the space. This is batched at the message level, so all the fields for the message have to have zero defaults to get the saves. By definition all proto3 syntax files fall into this case but it also saves space for the proto2 that use the standard defaults. (saves 8 bytes of static data for every field that had a zero default) - Don't track the enums defined by a message. Nothing in the runtime needs it and it was just generation and runtime overhead. (saves 8 bytes per enum) - Ensure EnumDescriptors are started up threadsafe in all cases. - Split some of the Descriptor initialization into multiple methods so the generated code isn't padded with lots of zero/nil args. - Change how oneof info is feed to the runtime enabling us to generate less static data (8 bytes saved per oneof for 64bit). - Change how enum value informat is capture to pack the data and only decode it if it ends up being needed. Avoids padding issues causing bloat of 64bit, and removes the needs for extra pointers in addition to the data (just the data and one pointer now).
2016-03-17 10:04:21 -04:00 · 2016-03-17 10:04:21 -04:00 · 79a23c435c
commit 79a23c435c
parent ca3dc15d4c
58 changed files with 1024 additions and 5169 deletions
--- a/Makefile.am
+++ b/Makefile.am
@ -381,13 +381,11 @@ objectivec_EXTRA_DIST=                                                       \
  objectivec/DevTools/full_mac_build.sh                                      \
  objectivec/DevTools/pddm.py                                                \
  objectivec/DevTools/pddm_tests.py                                          \
-  objectivec/generate_descriptors_proto.sh                                   \
+  objectivec/generate_well_known_types.sh                                    \
  objectivec/google/protobuf/Any.pbobjc.h                                    \
  objectivec/google/protobuf/Any.pbobjc.m                                    \
  objectivec/google/protobuf/Api.pbobjc.h                                    \
  objectivec/google/protobuf/Api.pbobjc.m                                    \
-  objectivec/google/protobuf/Descriptor.pbobjc.h                             \
-  objectivec/google/protobuf/Descriptor.pbobjc.m                             \
  objectivec/google/protobuf/Duration.pbobjc.h                               \
  objectivec/google/protobuf/Duration.pbobjc.m                               \
  objectivec/google/protobuf/Empty.pbobjc.h                                  \
--- a/Protobuf.podspec
+++ b/Protobuf.podspec
@ -17,7 +17,6 @@ Pod::Spec.new do |s|
  s.source_files = 'objectivec/*.{h,m}',
                   'objectivec/google/protobuf/Any.pbobjc.{h,m}',
                   'objectivec/google/protobuf/Api.pbobjc.{h,m}',
-                   'objectivec/google/protobuf/Descriptor.pbobjc.{h,m}',
                   'objectivec/google/protobuf/Duration.pbobjc.h',
                   'objectivec/google/protobuf/Empty.pbobjc.{h,m}',
                   'objectivec/google/protobuf/FieldMask.pbobjc.{h,m}',
--- a/generate_descriptor_proto.sh
+++ b/generate_descriptor_proto.sh
@ -92,9 +92,9 @@ do
 done
 cd ..

-if test -x objectivec/generate_descriptors_proto.sh; then
+if test -x objectivec/generate_well_known_types.sh; then
  echo "Generating messages for objc."
-  objectivec/generate_descriptors_proto.sh $@
+  objectivec/generate_well_known_types.sh $@
 fi

 if test -x csharp/generate_protos.sh; then
--- a/objectivec/DevTools/compile_testing_protos.sh
+++ b/objectivec/DevTools/compile_testing_protos.sh
@ -67,29 +67,36 @@ fi
 # Ensure the output dir exists
 mkdir -p "${OUTPUT_DIR}/google/protobuf"

-CORE_PROTO_FILES=(                                         \
-  src/google/protobuf/unittest_arena.proto                 \
-  src/google/protobuf/unittest_custom_options.proto        \
-  src/google/protobuf/unittest_enormous_descriptor.proto   \
-  src/google/protobuf/unittest_embed_optimize_for.proto    \
-  src/google/protobuf/unittest_empty.proto                 \
-  src/google/protobuf/unittest_import.proto                \
-  src/google/protobuf/unittest_import_lite.proto           \
-  src/google/protobuf/unittest_lite.proto                  \
-  src/google/protobuf/unittest_mset.proto                  \
-  src/google/protobuf/unittest_mset_wire_format.proto      \
-  src/google/protobuf/unittest_no_arena.proto              \
-  src/google/protobuf/unittest_no_arena_import.proto       \
-  src/google/protobuf/unittest_no_generic_services.proto   \
-  src/google/protobuf/unittest_optimize_for.proto          \
-  src/google/protobuf/unittest.proto                       \
-  src/google/protobuf/unittest_import_public.proto         \
-  src/google/protobuf/unittest_import_public_lite.proto    \
-  src/google/protobuf/unittest_drop_unknown_fields.proto   \
-  src/google/protobuf/unittest_preserve_unknown_enum.proto \
-  src/google/protobuf/map_lite_unittest.proto              \
-  src/google/protobuf/map_proto2_unittest.proto            \
-  src/google/protobuf/map_unittest.proto                   \
+CORE_PROTO_FILES=(
+  src/google/protobuf/unittest_arena.proto
+  src/google/protobuf/unittest_custom_options.proto
+  src/google/protobuf/unittest_enormous_descriptor.proto
+  src/google/protobuf/unittest_embed_optimize_for.proto
+  src/google/protobuf/unittest_empty.proto
+  src/google/protobuf/unittest_import.proto
+  src/google/protobuf/unittest_import_lite.proto
+  src/google/protobuf/unittest_lite.proto
+  src/google/protobuf/unittest_mset.proto
+  src/google/protobuf/unittest_mset_wire_format.proto
+  src/google/protobuf/unittest_no_arena.proto
+  src/google/protobuf/unittest_no_arena_import.proto
+  src/google/protobuf/unittest_no_generic_services.proto
+  src/google/protobuf/unittest_optimize_for.proto
+  src/google/protobuf/unittest.proto
+  src/google/protobuf/unittest_import_public.proto
+  src/google/protobuf/unittest_import_public_lite.proto
+  src/google/protobuf/unittest_drop_unknown_fields.proto
+  src/google/protobuf/unittest_preserve_unknown_enum.proto
+  src/google/protobuf/map_lite_unittest.proto
+  src/google/protobuf/map_proto2_unittest.proto
+  src/google/protobuf/map_unittest.proto
+)
+
+# The unittest_custom_options.proto extends the messages in descriptor.proto
+# so we build it in to test extending in general. The library doesn't provide
+# a descriptor as it doesn't use the classes/enums.
+CORE_PROTO_FILES+=(
+  src/google/protobuf/descriptor.proto
 )

 compile_proto() {
@ -104,12 +111,12 @@ for a_proto in "${CORE_PROTO_FILES[@]}" ; do
  compile_proto "${a_proto}"
 done

-OBJC_PROTO_FILES=(                               \
-  objectivec/Tests/unittest_cycle.proto          \
-  objectivec/Tests/unittest_runtime_proto2.proto \
-  objectivec/Tests/unittest_runtime_proto3.proto \
-  objectivec/Tests/unittest_objc.proto           \
-  objectivec/Tests/unittest_objc_startup.proto   \
+OBJC_PROTO_FILES=(
+  objectivec/Tests/unittest_cycle.proto
+  objectivec/Tests/unittest_runtime_proto2.proto
+  objectivec/Tests/unittest_runtime_proto3.proto
+  objectivec/Tests/unittest_objc.proto
+  objectivec/Tests/unittest_objc_startup.proto
 )

 for a_proto in "${OBJC_PROTO_FILES[@]}" ; do
--- a/objectivec/DevTools/full_mac_build.sh
+++ b/objectivec/DevTools/full_mac_build.sh
@ -190,7 +190,7 @@ header "Ensuring the ObjC descriptors are current."
 readonly NewestInput=$(find \
   src/google/protobuf/*.proto \
   src/.libs src/*.la src/protoc \
-   objectivec/generate_descriptors_proto.sh \
+   objectivec/generate_well_known_types.sh \
      -type f -print0 \
      | xargs -0 stat -f "%m %N" \
      | sort -n | tail -n1 | cut -f2- -d" ")
@ -203,7 +203,7 @@ readonly OldestOutput=$(find \
 # If the newest input is newer than the oldest output, regenerate.
 if [[ "${NewestInput}" -nt "${OldestOutput}" ]] ; then
  echo ">> Newest input is newer than oldest output, regenerating."
-  objectivec/generate_descriptors_proto.sh -j "${NUM_MAKE_JOBS}"
+  objectivec/generate_well_known_types.sh -j "${NUM_MAKE_JOBS}"
 else
  echo ">> Newest input is older than oldest output, no need to regenerating."
 fi
--- a/objectivec/GPBBootstrap.h
+++ b/objectivec/GPBBootstrap.h
@ -37,13 +37,6 @@
 #define GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS 0
 #endif

-// Most uses of protocol buffers don't need field options, by default the
-// static data will be compiled out, define this to 1 to include it. The only
-// time you need this is if you are doing introspection of the protocol buffers.
-#ifndef GPBOBJC_INCLUDE_FIELD_OPTIONS
-#define GPBOBJC_INCLUDE_FIELD_OPTIONS 0
-#endif
-
 // Used in the generated code to give sizes to enums. int32_t was chosen based
 // on the fact that Protocol Buffers enums are limited to this range.
 #if !__has_feature(objc_fixed_enum)
@ -89,4 +82,4 @@
 // generated Objective C sources.  In general we don't want to change the
 // runtime interfaces (or this version) as it means everything has to be
 // regenerated.
-#define GOOGLE_PROTOBUF_OBJC_GEN_VERSION 30000
+#define GOOGLE_PROTOBUF_OBJC_GEN_VERSION 30001
--- a/objectivec/GPBDescriptor.h
+++ b/objectivec/GPBDescriptor.h
@ -34,19 +34,18 @@

@class GPBEnumDescriptor;
@class GPBFieldDescriptor;
-@class GPBFieldOptions;
@class GPBFileDescriptor;
@class GPBOneofDescriptor;

 NS_ASSUME_NONNULL_BEGIN

-typedef NS_ENUM(NSInteger, GPBFileSyntax) {
+typedef NS_ENUM(uint8_t, GPBFileSyntax) {
  GPBFileSyntaxUnknown = 0,
  GPBFileSyntaxProto2 = 2,
  GPBFileSyntaxProto3 = 3,
 };

-typedef NS_ENUM(NSInteger, GPBFieldType) {
+typedef NS_ENUM(uint8_t, GPBFieldType) {
  GPBFieldTypeSingle,    // optional/required
  GPBFieldTypeRepeated,  // repeated
  GPBFieldTypeMap,       // map<K,V>
@ -57,9 +56,8 @@ typedef NS_ENUM(NSInteger, GPBFieldType) {
@property(nonatomic, readonly, copy) NSString *name;
@property(nonatomic, readonly, strong, nullable) NSArray<GPBFieldDescriptor*> *fields;
@property(nonatomic, readonly, strong, nullable) NSArray<GPBOneofDescriptor*> *oneofs;
-@property(nonatomic, readonly, strong, nullable) NSArray<GPBEnumDescriptor*> *enums;
@property(nonatomic, readonly, nullable) const GPBExtensionRange *extensionRanges;
-@property(nonatomic, readonly) NSUInteger extensionRangesCount;
+@property(nonatomic, readonly) uint32_t extensionRangesCount;
@property(nonatomic, readonly, assign) GPBFileDescriptor *file;

@property(nonatomic, readonly, getter=isWireFormat) BOOL wireFormat;
@ -68,7 +66,6 @@ typedef NS_ENUM(NSInteger, GPBFieldType) {
 - (nullable GPBFieldDescriptor *)fieldWithNumber:(uint32_t)fieldNumber;
 - (nullable GPBFieldDescriptor *)fieldWithName:(NSString *)name;
 - (nullable GPBOneofDescriptor *)oneofWithName:(NSString *)name;
- (nullable GPBEnumDescriptor *)enumWithName:(NSString *)name;

@end

@ -103,8 +100,6 @@ typedef NS_ENUM(NSInteger, GPBFieldType) {

@property(nonatomic, readonly, assign, nullable) GPBOneofDescriptor *containingOneof;

-@property(nonatomic, readonly, nullable) GPBFieldOptions *fieldOptions;
-
 // Message properties
@property(nonatomic, readonly, assign, nullable) Class msgClass;

--- a/objectivec/GPBDescriptor.m
+++ b/objectivec/GPBDescriptor.m
@ -35,7 +35,6 @@
 #import "GPBUtilities_PackagePrivate.h"
 #import "GPBWireFormat.h"
 #import "GPBMessage_PackagePrivate.h"
-#import "google/protobuf/Descriptor.pbobjc.h"

 // The address of this variable is used as a key for obj_getAssociatedObject.
 static const char kTextFormatExtraValueKey = 0;
@ -92,7 +91,6 @@ static NSArray *NewFieldsArrayForHasIndex(int hasIndex,

@implementation GPBDescriptor {
  Class messageClass_;
-  NSArray *enums_;
  GPBFileDescriptor *file_;
  BOOL wireFormat_;
 }
@ -100,7 +98,6 @@ static NSArray *NewFieldsArrayForHasIndex(int hasIndex,
@synthesize messageClass = messageClass_;
@synthesize fields = fields_;
@synthesize oneofs = oneofs_;
-@synthesize enums = enums_;
@synthesize extensionRanges = extensionRanges_;
@synthesize extensionRangesCount = extensionRangesCount_;
@synthesize file = file_;
@ -110,130 +107,58 @@ static NSArray *NewFieldsArrayForHasIndex(int hasIndex,
    allocDescriptorForClass:(Class)messageClass
                  rootClass:(Class)rootClass
                       file:(GPBFileDescriptor *)file
-                     fields:(GPBMessageFieldDescription *)fieldDescriptions
-                 fieldCount:(NSUInteger)fieldCount
-                     oneofs:(GPBMessageOneofDescription *)oneofDescriptions
-                 oneofCount:(NSUInteger)oneofCount
-                      enums:(GPBMessageEnumDescription *)enumDescriptions
-                  enumCount:(NSUInteger)enumCount
-                     ranges:(const GPBExtensionRange *)ranges
-                 rangeCount:(NSUInteger)rangeCount
-                storageSize:(size_t)storageSize
-                 wireFormat:(BOOL)wireFormat {
+                     fields:(void *)fieldDescriptions
+                 fieldCount:(uint32_t)fieldCount
+                storageSize:(uint32_t)storageSize
+                      flags:(GPBDescriptorInitializationFlags)flags {
+  // The rootClass is no longer used, but it is passed in to ensure it
+  // was started up during initialization also.
+  (void)rootClass;
  NSMutableArray *fields = nil;
-  NSMutableArray *oneofs = nil;
-  NSMutableArray *enums = nil;
-  NSMutableArray *extensionRanges = nil;
  GPBFileSyntax syntax = file.syntax;
-  for (NSUInteger i = 0; i < fieldCount; ++i) {
+  BOOL fieldsIncludeDefault =
+      (flags & GPBDescriptorInitializationFlag_FieldsWithDefault) != 0;
+
+  void *desc;
+  for (uint32_t i = 0; i < fieldCount; ++i) {
    if (fields == nil) {
      fields = [[NSMutableArray alloc] initWithCapacity:fieldCount];
    }
-    GPBFieldDescriptor *fieldDescriptor = [[GPBFieldDescriptor alloc]
-        initWithFieldDescription:&fieldDescriptions[i]
-                       rootClass:rootClass
-                          syntax:syntax];
+    // Need correctly typed pointer for array indexing below to work.
+    if (fieldsIncludeDefault) {
+      GPBMessageFieldDescriptionWithDefault *fieldDescWithDefault = fieldDescriptions;
+      desc = &(fieldDescWithDefault[i]);
+    } else {
+      GPBMessageFieldDescription *fieldDesc = fieldDescriptions;
+      desc = &(fieldDesc[i]);
+    }
+    GPBFieldDescriptor *fieldDescriptor =
+        [[GPBFieldDescriptor alloc] initWithFieldDescription:desc
+                                             includesDefault:fieldsIncludeDefault
+                                                      syntax:syntax];
    [fields addObject:fieldDescriptor];
    [fieldDescriptor release];
  }
-  for (NSUInteger i = 0; i < oneofCount; ++i) {
-    if (oneofs == nil) {
-      oneofs = [[NSMutableArray alloc] initWithCapacity:oneofCount];
-    }
-    GPBMessageOneofDescription *oneofDescription = &oneofDescriptions[i];
-    NSArray *fieldsForOneof =
-        NewFieldsArrayForHasIndex(oneofDescription->index, fields);
-    GPBOneofDescriptor *oneofDescriptor =
-        [[GPBOneofDescriptor alloc] initWithOneofDescription:oneofDescription
-                                                      fields:fieldsForOneof];
-    [oneofs addObject:oneofDescriptor];
-    [oneofDescriptor release];
-    [fieldsForOneof release];
-  }
-  for (NSUInteger i = 0; i < enumCount; ++i) {
-    if (enums == nil) {
-      enums = [[NSMutableArray alloc] initWithCapacity:enumCount];
-    }
-    GPBEnumDescriptor *enumDescriptor =
-        enumDescriptions[i].enumDescriptorFunc();
-    [enums addObject:enumDescriptor];
-  }

+  BOOL wireFormat = (flags & GPBDescriptorInitializationFlag_WireFormat) != 0;
  GPBDescriptor *descriptor = [[self alloc] initWithClass:messageClass
                                                     file:file
                                                   fields:fields
-                                                   oneofs:oneofs
-                                                    enums:enums
-                                          extensionRanges:ranges
-                                     extensionRangesCount:rangeCount
                                              storageSize:storageSize
                                               wireFormat:wireFormat];
  [fields release];
-  [oneofs release];
-  [enums release];
-  [extensionRanges release];
-  return descriptor;
-}
-
-+ (instancetype)
-    allocDescriptorForClass:(Class)messageClass
-                  rootClass:(Class)rootClass
-                       file:(GPBFileDescriptor *)file
-                     fields:(GPBMessageFieldDescription *)fieldDescriptions
-                 fieldCount:(NSUInteger)fieldCount
-                     oneofs:(GPBMessageOneofDescription *)oneofDescriptions
-                 oneofCount:(NSUInteger)oneofCount
-                      enums:(GPBMessageEnumDescription *)enumDescriptions
-                  enumCount:(NSUInteger)enumCount
-                     ranges:(const GPBExtensionRange *)ranges
-                 rangeCount:(NSUInteger)rangeCount
-                storageSize:(size_t)storageSize
-                 wireFormat:(BOOL)wireFormat
-        extraTextFormatInfo:(const char *)extraTextFormatInfo {
-  GPBDescriptor *descriptor = [self allocDescriptorForClass:messageClass
-                                                  rootClass:rootClass
-                                                       file:file
-                                                     fields:fieldDescriptions
-                                                 fieldCount:fieldCount
-                                                     oneofs:oneofDescriptions
-                                                 oneofCount:oneofCount
-                                                      enums:enumDescriptions
-                                                  enumCount:enumCount
-                                                     ranges:ranges
-                                                 rangeCount:rangeCount
-                                                storageSize:storageSize
-                                                 wireFormat:wireFormat];
-  // Extra info is a compile time option, so skip the work if not needed.
-  if (extraTextFormatInfo) {
-    NSValue *extraInfoValue = [NSValue valueWithPointer:extraTextFormatInfo];
-    for (GPBFieldDescriptor *fieldDescriptor in descriptor->fields_) {
-      if (fieldDescriptor->description_->flags & GPBFieldTextFormatNameCustom) {
-        objc_setAssociatedObject(fieldDescriptor, &kTextFormatExtraValueKey,
-                                 extraInfoValue,
-                                 OBJC_ASSOCIATION_RETAIN_NONATOMIC);
-      }
-    }
-  }
  return descriptor;
 }

 - (instancetype)initWithClass:(Class)messageClass
                         file:(GPBFileDescriptor *)file
                       fields:(NSArray *)fields
-                       oneofs:(NSArray *)oneofs
-                        enums:(NSArray *)enums
-              extensionRanges:(const GPBExtensionRange *)extensionRanges
-         extensionRangesCount:(NSUInteger)extensionRangesCount
-                  storageSize:(size_t)storageSize
+                  storageSize:(uint32_t)storageSize
                   wireFormat:(BOOL)wireFormat {
  if ((self = [super init])) {
    messageClass_ = messageClass;
    file_ = file;
    fields_ = [fields retain];
-    oneofs_ = [oneofs retain];
-    enums_ = [enums retain];
-    extensionRanges_ = extensionRanges;
-    extensionRangesCount_ = extensionRangesCount;
    storageSize_ = storageSize;
    wireFormat_ = wireFormat;
  }
@ -243,10 +168,47 @@ static NSArray *NewFieldsArrayForHasIndex(int hasIndex,
 - (void)dealloc {
  [fields_ release];
  [oneofs_ release];
-  [enums_ release];
  [super dealloc];
 }

+- (void)setupOneofs:(const char **)oneofNames
+              count:(uint32_t)count
+      firstHasIndex:(int32_t)firstHasIndex {
+  NSCAssert(firstHasIndex < 0, @"Should always be <0");
+  NSMutableArray *oneofs = [[NSMutableArray alloc] initWithCapacity:count];
+  for (uint32_t i = 0, hasIndex = firstHasIndex; i < count; ++i, --hasIndex) {
+    const char *name = oneofNames[i];
+    NSArray *fieldsForOneof = NewFieldsArrayForHasIndex(hasIndex, fields_);
+    NSCAssert(fieldsForOneof.count > 0,
+              @"No fields for this oneof? (%s:%d)", name, hasIndex);
+    GPBOneofDescriptor *oneofDescriptor =
+        [[GPBOneofDescriptor alloc] initWithName:name fields:fieldsForOneof];
+    [oneofs addObject:oneofDescriptor];
+    [oneofDescriptor release];
+    [fieldsForOneof release];
+  }
+  oneofs_ = oneofs;
+}
+
+- (void)setupExtraTextInfo:(const char *)extraTextFormatInfo {
+  // Extra info is a compile time option, so skip the work if not needed.
+  if (extraTextFormatInfo) {
+    NSValue *extraInfoValue = [NSValue valueWithPointer:extraTextFormatInfo];
+    for (GPBFieldDescriptor *fieldDescriptor in fields_) {
+      if (fieldDescriptor->description_->flags & GPBFieldTextFormatNameCustom) {
+        objc_setAssociatedObject(fieldDescriptor, &kTextFormatExtraValueKey,
+                                 extraInfoValue,
+                                 OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+      }
+    }
+  }
+}
+
+- (void)setupExtensionRanges:(const GPBExtensionRange *)ranges count:(int32_t)count {
+  extensionRanges_ = ranges;
+  extensionRangesCount_ = count;
+}
+
 - (NSString *)name {
  return NSStringFromClass(messageClass_);
 }
@ -283,15 +245,6 @@ static NSArray *NewFieldsArrayForHasIndex(int hasIndex,
  return nil;
 }

- (GPBEnumDescriptor *)enumWithName:(NSString *)name {
-  for (GPBEnumDescriptor *descriptor in enums_) {
-    if ([descriptor.name isEqual:name]) {
-      return descriptor;
-    }
-  }
-  return nil;
-}
-
@end

@implementation GPBFileDescriptor {
@ -318,19 +271,16 @@ static NSArray *NewFieldsArrayForHasIndex(int hasIndex,

@synthesize fields = fields_;

- (instancetype)initWithOneofDescription:
-                    (GPBMessageOneofDescription *)oneofDescription
-                                  fields:(NSArray *)fields {
+- (instancetype)initWithName:(const char *)name fields:(NSArray *)fields {
  self = [super init];
  if (self) {
-    NSAssert(oneofDescription->index < 0, @"Should always be <0");
-    oneofDescription_ = oneofDescription;
+    name_ = name;
    fields_ = [fields retain];
    for (GPBFieldDescriptor *fieldDesc in fields) {
      fieldDesc->containingOneof_ = self;
    }

-    caseSel_ = SelFromStrings(NULL, oneofDescription->name, "OneOfCase", NO);
+    caseSel_ = SelFromStrings(NULL, name, "OneOfCase", NO);
  }
  return self;
 }
@ -341,7 +291,7 @@ static NSArray *NewFieldsArrayForHasIndex(int hasIndex,
 }

 - (NSString *)name {
-  return @(oneofDescription_->name);
+  return @(name_);
 }

 - (GPBFieldDescriptor *)fieldWithNumber:(uint32_t)fieldNumber {
@ -389,7 +339,6 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {

@implementation GPBFieldDescriptor {
  GPBGenericValue defaultValue_;
-  GPBFieldOptions *fieldOptions_;

  // Message ivars
  Class msgClass_;
@ -403,7 +352,6 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
  } enumHandling_;
 }

-@synthesize fieldOptions = fieldOptions_;
@synthesize msgClass = msgClass_;
@synthesize containingOneof = containingOneof_;

@ -417,16 +365,21 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
  return self;
 }

- (instancetype)initWithFieldDescription:
-                    (GPBMessageFieldDescription *)description
-                               rootClass:(Class)rootClass
+- (instancetype)initWithFieldDescription:(void *)description
+                         includesDefault:(BOOL)includesDefault
                                  syntax:(GPBFileSyntax)syntax {
  if ((self = [super init])) {
-    description_ = description;
-    getSel_ = sel_getUid(description->name);
-    setSel_ = SelFromStrings("set", description->name, NULL, YES);
+    GPBMessageFieldDescription *coreDesc;
+    if (includesDefault) {
+      coreDesc = &(((GPBMessageFieldDescriptionWithDefault *)description)->core);
+    } else {
+      coreDesc = description;
+    }
+    description_ = coreDesc;
+    getSel_ = sel_getUid(coreDesc->name);
+    setSel_ = SelFromStrings("set", coreDesc->name, NULL, YES);

-    GPBDataType dataType = description->dataType;
+    GPBDataType dataType = coreDesc->dataType;
    BOOL isMessage = GPBDataTypeIsMessage(dataType);
    BOOL isMapOrArray = GPBFieldIsMapOrArray(self);

@ -434,39 +387,39 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
      // map<>/repeated fields get a *Count property (inplace of a has*) to
      // support checking if there are any entries without triggering
      // autocreation.
-      hasOrCountSel_ = SelFromStrings(NULL, description->name, "_Count", NO);
+      hasOrCountSel_ = SelFromStrings(NULL, coreDesc->name, "_Count", NO);
    } else {
      // If there is a positive hasIndex, then:
      //   - All fields types for proto2 messages get has* selectors.
      //   - Only message fields for proto3 messages get has* selectors.
      // Note: the positive check is to handle oneOfs, we can't check
      // containingOneof_ because it isn't set until after initialization.
-      if ((description->hasIndex >= 0) &&
-          (description->hasIndex != GPBNoHasBit) &&
+      if ((coreDesc->hasIndex >= 0) &&
+          (coreDesc->hasIndex != GPBNoHasBit) &&
          ((syntax != GPBFileSyntaxProto3) || isMessage)) {
-        hasOrCountSel_ = SelFromStrings("has", description->name, NULL, NO);
-        setHasSel_ = SelFromStrings("setHas", description->name, NULL, YES);
+        hasOrCountSel_ = SelFromStrings("has", coreDesc->name, NULL, NO);
+        setHasSel_ = SelFromStrings("setHas", coreDesc->name, NULL, YES);
      }
    }

    // Extra type specific data.
    if (isMessage) {
-      const char *className = description->dataTypeSpecific.className;
+      const char *className = coreDesc->dataTypeSpecific.className;
      msgClass_ = objc_getClass(className);
      NSAssert(msgClass_, @"Class %s not defined", className);
    } else if (dataType == GPBDataTypeEnum) {
-      if ((description_->flags & GPBFieldHasEnumDescriptor) != 0) {
+      if ((coreDesc->flags & GPBFieldHasEnumDescriptor) != 0) {
        enumHandling_.enumDescriptor_ =
-            description->dataTypeSpecific.enumDescFunc();
+            coreDesc->dataTypeSpecific.enumDescFunc();
      } else {
        enumHandling_.enumVerifier_ =
-            description->dataTypeSpecific.enumVerifier;
+            coreDesc->dataTypeSpecific.enumVerifier;
      }
    }

-    // Non map<>/repeated fields can have defaults.
-    if (!isMapOrArray) {
-      defaultValue_ = description->defaultValue;
+    // Non map<>/repeated fields can have defaults in proto2 syntax.
+    if (!isMapOrArray && includesDefault) {
+      defaultValue_ = ((GPBMessageFieldDescriptionWithDefault *)description)->defaultValue;
      if (dataType == GPBDataTypeBytes) {
        // Data stored as a length prefixed (network byte order) c-string in
        // descriptor structure.
@ -480,24 +433,6 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
        }
      }
    }
-
-    // FieldOptions stored as a length prefixed (network byte order) c-escaped
-    // string in descriptor records.
-    if (description->fieldOptions) {
-      uint8_t *optionsBytes = (uint8_t *)description->fieldOptions;
-      uint32_t optionsLength = *((uint32_t *)optionsBytes);
-      optionsLength = ntohl(optionsLength);
-      if (optionsLength > 0) {
-        optionsBytes += sizeof(optionsLength);
-        NSData *optionsData = [NSData dataWithBytesNoCopy:optionsBytes
-                                                   length:optionsLength
-                                             freeWhenDone:NO];
-        GPBExtensionRegistry *registry = [rootClass extensionRegistry];
-        fieldOptions_ = [[GPBFieldOptions parseFromData:optionsData
-                                      extensionRegistry:registry
-                                                  error:NULL] retain];
-      }
-    }
  }
  return self;
 }
@ -666,7 +601,7 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
  } else {
    // Undo the CamelCase.
    NSMutableString *result = [NSMutableString stringWithCapacity:len];
-    for (NSUInteger i = 0; i < len; i++) {
+    for (uint32_t i = 0; i < len; i++) {
      unichar c = [name characterAtIndex:i];
      if (c >= 'A' && c <= 'Z') {
        if (i > 0) {
@ -686,10 +621,16 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {

@implementation GPBEnumDescriptor {
  NSString *name_;
-  GPBMessageEnumValueDescription *valueDescriptions_;
-  NSUInteger valueDescriptionsCount_;
+  // valueNames_ is a single c string with all of the value names appended
+  // together, each null terminated.  -calcValueNameOffsets fills in
+  // nameOffsets_ with the offsets to allow quicker access to the individual
+  // names.
+  const char *valueNames_;
+  const int32_t *values_;
  GPBEnumValidationFunc enumVerifier_;
  const uint8_t *extraTextFormatInfo_;
+  uint32_t *nameOffsets_;
+  uint32_t valueCount_;
 }

@synthesize name = name_;
@ -697,26 +638,30 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {

 + (instancetype)
    allocDescriptorForName:(NSString *)name
-                    values:(GPBMessageEnumValueDescription *)valueDescriptions
-                valueCount:(NSUInteger)valueCount
+                valueNames:(const char *)valueNames
+                    values:(const int32_t *)values
+                     count:(uint32_t)valueCount
              enumVerifier:(GPBEnumValidationFunc)enumVerifier {
  GPBEnumDescriptor *descriptor = [[self alloc] initWithName:name
-                                                      values:valueDescriptions
-                                                  valueCount:valueCount
+                                                  valueNames:valueNames
+                                                      values:values
+                                                       count:valueCount
                                                enumVerifier:enumVerifier];
  return descriptor;
 }

 + (instancetype)
    allocDescriptorForName:(NSString *)name
-                    values:(GPBMessageEnumValueDescription *)valueDescriptions
-                valueCount:(NSUInteger)valueCount
+                valueNames:(const char *)valueNames
+                    values:(const int32_t *)values
+                     count:(uint32_t)valueCount
              enumVerifier:(GPBEnumValidationFunc)enumVerifier
       extraTextFormatInfo:(const char *)extraTextFormatInfo {
  // Call the common case.
  GPBEnumDescriptor *descriptor = [self allocDescriptorForName:name
-                                                        values:valueDescriptions
-                                                    valueCount:valueCount
+                                                    valueNames:valueNames
+                                                        values:values
+                                                         count:valueCount
                                                  enumVerifier:enumVerifier];
  // Set the extra info.
  descriptor->extraTextFormatInfo_ = (const uint8_t *)extraTextFormatInfo;
@ -724,24 +669,49 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
 }

 - (instancetype)initWithName:(NSString *)name
-                      values:(GPBMessageEnumValueDescription *)valueDescriptions
-                  valueCount:(NSUInteger)valueCount
+                  valueNames:(const char *)valueNames
+                      values:(const int32_t *)values
+                       count:(uint32_t)valueCount
                enumVerifier:(GPBEnumValidationFunc)enumVerifier {
  if ((self = [super init])) {
    name_ = [name copy];
-    valueDescriptions_ = valueDescriptions;
-    valueDescriptionsCount_ = valueCount;
+    valueNames_ = valueNames;
+    values_ = values;
+    valueCount_ = valueCount;
    enumVerifier_ = enumVerifier;
  }
  return self;
 }

+- (void)dealloc {
+  [name_ release];
+  if (nameOffsets_) free(nameOffsets_);
+  [super dealloc];
+}
+
+- (void)calcValueNameOffsets {
+  @synchronized(self) {
+    if (nameOffsets_ != NULL) {
+      return;
+    }
+    uint32_t *offsets = malloc(valueCount_ * sizeof(uint32_t));
+    const char *scan = valueNames_;
+    for (uint32_t i = 0; i < valueCount_; ++i) {
+      offsets[i] = (uint32_t)(scan - valueNames_);
+      while (*scan != '\0') ++scan;
+      ++scan;  // Step over the null.
+    }
+    nameOffsets_ = offsets;
+  }
+}
+
 - (NSString *)enumNameForValue:(int32_t)number {
-  for (NSUInteger i = 0; i < valueDescriptionsCount_; ++i) {
-    GPBMessageEnumValueDescription *scan = &valueDescriptions_[i];
-    if ((scan->number == number) && (scan->name != NULL)) {
-      NSString *fullName =
-          [NSString stringWithFormat:@"%@_%s", name_, scan->name];
+  if (nameOffsets_ == NULL) [self calcValueNameOffsets];
+
+  for (uint32_t i = 0; i < valueCount_; ++i) {
+    if (values_[i] == number) {
+      const char *valueName = valueNames_ + nameOffsets_[i];
+      NSString *fullName = [NSString stringWithFormat:@"%@_%s", name_, valueName];
      return fullName;
    }
  }
@ -760,12 +730,14 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
  const char *nameAsCStr = [name UTF8String];
  nameAsCStr += prefixLen;

+  if (nameOffsets_ == NULL) [self calcValueNameOffsets];
+
  // Find it.
-  for (NSUInteger i = 0; i < valueDescriptionsCount_; ++i) {
-    GPBMessageEnumValueDescription *scan = &valueDescriptions_[i];
-    if ((scan->name != NULL) && (strcmp(nameAsCStr, scan->name) == 0)) {
+  for (uint32_t i = 0; i < valueCount_; ++i) {
+    const char *valueName = valueNames_ + nameOffsets_[i];
+    if (strcmp(nameAsCStr, valueName) == 0) {
      if (outValue) {
-        *outValue = scan->number;
+        *outValue = values_[i];
      }
      return YES;
    }
@ -773,34 +745,28 @@ uint32_t GPBFieldAlternateTag(GPBFieldDescriptor *self) {
  return NO;
 }

- (void)dealloc {
-  [name_ release];
-  [super dealloc];
-}
-
 - (NSString *)textFormatNameForValue:(int32_t)number {
+  if (nameOffsets_ == NULL) [self calcValueNameOffsets];
+
  // Find the EnumValue descriptor and its index.
-  GPBMessageEnumValueDescription *valueDescriptor = NULL;
-  NSUInteger valueDescriptorIndex;
-  for (valueDescriptorIndex = 0; valueDescriptorIndex < valueDescriptionsCount_;
+  BOOL foundIt = NO;
+  uint32_t valueDescriptorIndex;
+  for (valueDescriptorIndex = 0; valueDescriptorIndex < valueCount_;
       ++valueDescriptorIndex) {
-    GPBMessageEnumValueDescription *scan =
-        &valueDescriptions_[valueDescriptorIndex];
-    if (scan->number == number) {
-      valueDescriptor = scan;
+    if (values_[valueDescriptorIndex] == number) {
+      foundIt = YES;
      break;
    }
  }

-  // If we didn't find it, or names were disable at proto compile time, nothing
-  // we can do.
-  if (!valueDescriptor || !valueDescriptor->name) {
+  if (!foundIt) {
    return nil;
  }

  NSString *result = nil;
  // Naming adds an underscore between enum name and value name, skip that also.
-  NSString *shortName = @(valueDescriptor->name);
+  const char *valueName = valueNames_ + nameOffsets_[valueDescriptorIndex];
+  NSString *shortName = @(valueName);

  // See if it is in the map of special format handling.
  if (extraTextFormatInfo_) {
--- a/objectivec/GPBDescriptor_PackagePrivate.h
+++ b/objectivec/GPBDescriptor_PackagePrivate.h
@ -36,7 +36,7 @@
 #import "GPBWireFormat.h"

 // Describes attributes of the field.
-typedef NS_OPTIONS(uint32_t, GPBFieldFlags) {
+typedef NS_OPTIONS(uint16_t, GPBFieldFlags) {
  // These map to standard protobuf concepts.
  GPBFieldRequired        = 1 << 0,
  GPBFieldRepeated        = 1 << 1,
@ -44,6 +44,12 @@ typedef NS_OPTIONS(uint32_t, GPBFieldFlags) {
  GPBFieldOptional        = 1 << 3,
  GPBFieldHasDefaultValue = 1 << 4,

+  // Indicates the field needs custom handling for the TextFormat name, if not
+  // set, the name can be derived from the ObjC name.
+  GPBFieldTextFormatNameCustom = 1 << 6,
+  // Indicates the field has an enum descriptor.
+  GPBFieldHasEnumDescriptor = 1 << 7,
+
  // These are not standard protobuf concepts, they are specific to the
  // Objective C runtime.

@ -62,35 +68,16 @@ typedef NS_OPTIONS(uint32_t, GPBFieldFlags) {
  GPBFieldMapKeySFixed64 = 10 << 8,
  GPBFieldMapKeyBool     = 11 << 8,
  GPBFieldMapKeyString   = 12 << 8,
-
-  // Indicates the field needs custom handling for the TextFormat name, if not
-  // set, the name can be derived from the ObjC name.
-  GPBFieldTextFormatNameCustom = 1 << 16,
-  // Indicates the field has an enum descriptor.
-  GPBFieldHasEnumDescriptor = 1 << 17,
 };

+// NOTE: The structures defined here have their members ordered to minimize
+// their size. This directly impacts the size of apps since these exist per
+// field/extension.
+
 // Describes a single field in a protobuf as it is represented as an ivar.
 typedef struct GPBMessageFieldDescription {
  // Name of ivar.
  const char *name;
-  // The field number for the ivar.
-  uint32_t number;
-  // The index (in bits) into _has_storage_.
-  //   > 0: the bit to use for a value being set.
-  //   = 0: no storage used.
-  //   < 0: in a oneOf, use a full int32 to record the field active.
-  int32_t hasIndex;
-  // Field flags. Use accessor functions below.
-  GPBFieldFlags flags;
-  // Data type of the ivar.
-  GPBDataType dataType;
-  // Offset of the variable into it's structure struct.
-  size_t offset;
-  // FieldOptions protobuf, serialized as string.
-  const char *fieldOptions;
-
-  GPBGenericValue defaultValue;  // Default value for the ivar.
  union {
    const char *className;  // Name for message class.
    // For enums only: If EnumDescriptors are compiled in, it will be that,
@ -98,31 +85,32 @@ typedef struct GPBMessageFieldDescription {
    GPBEnumDescriptorFunc enumDescFunc;
    GPBEnumValidationFunc enumVerifier;
  } dataTypeSpecific;
+  // The field number for the ivar.
+  uint32_t number;
+  // The index (in bits) into _has_storage_.
+  //   >= 0: the bit to use for a value being set.
+  //   = GPBNoHasBit(INT32_MAX): no storage used.
+  //   < 0: in a oneOf, use a full int32 to record the field active.
+  int32_t hasIndex;
+  // Offset of the variable into it's structure struct.
+  uint32_t offset;
+  // Field flags. Use accessor functions below.
+  GPBFieldFlags flags;
+  // Data type of the ivar.
+  GPBDataType dataType;
 } GPBMessageFieldDescription;

-// Describes a oneof.
-typedef struct GPBMessageOneofDescription {
-  // Name of this enum oneof.
-  const char *name;
-  // The index of this oneof in the has_storage.
-  int32_t index;
-} GPBMessageOneofDescription;
+// Fields in messages defined in a 'proto2' syntax file can provide a default
+// value. This struct provides the default along with the field info.
+typedef struct GPBMessageFieldDescriptionWithDefault {
+  // Default value for the ivar.
+  GPBGenericValue defaultValue;

-// Describes an enum type defined in a .proto file.
-typedef struct GPBMessageEnumDescription {
-  GPBEnumDescriptorFunc enumDescriptorFunc;
-} GPBMessageEnumDescription;
-
-// Describes an individual enum constant of a particular type.
-typedef struct GPBMessageEnumValueDescription {
-  // Name of this enum constant.
-  const char *name;
-  // Numeric value of this enum constant.
-  int32_t number;
-} GPBMessageEnumValueDescription;
+  GPBMessageFieldDescription core;
+} GPBMessageFieldDescriptionWithDefault;

 // Describes attributes of the extension.
-typedef NS_OPTIONS(uint32_t, GPBExtensionOptions) {
+typedef NS_OPTIONS(uint8_t, GPBExtensionOptions) {
  // These map to standard protobuf concepts.
  GPBExtensionRepeated      = 1 << 0,
  GPBExtensionPacked        = 1 << 1,
@ -131,65 +119,53 @@ typedef NS_OPTIONS(uint32_t, GPBExtensionOptions) {

 // An extension
 typedef struct GPBExtensionDescription {
-  const char *singletonName;
-  GPBDataType dataType;
-  const char *extendedClass;
-  int32_t fieldNumber;
  GPBGenericValue defaultValue;
+  const char *singletonName;
+  const char *extendedClass;
  const char *messageOrGroupClassName;
-  GPBExtensionOptions options;
  GPBEnumDescriptorFunc enumDescriptorFunc;
+  int32_t fieldNumber;
+  GPBDataType dataType;
+  GPBExtensionOptions options;
 } GPBExtensionDescription;

+typedef NS_OPTIONS(uint32_t, GPBDescriptorInitializationFlags) {
+  GPBDescriptorInitializationFlag_FieldsWithDefault = 1 << 0,
+  GPBDescriptorInitializationFlag_WireFormat        = 1 << 1,
+};
+
@interface GPBDescriptor () {
 @package
  NSArray *fields_;
  NSArray *oneofs_;
-  size_t storageSize_;
+  uint32_t storageSize_;
 }

-// fieldDescriptions, enumDescriptions, rangeDescriptions, and
-// extraTextFormatInfo have to be long lived, they are held as raw pointers.
+// fieldDescriptions have to be long lived, they are held as raw pointers.
 + (instancetype)
    allocDescriptorForClass:(Class)messageClass
                  rootClass:(Class)rootClass
                       file:(GPBFileDescriptor *)file
-                     fields:(GPBMessageFieldDescription *)fieldDescriptions
-                 fieldCount:(NSUInteger)fieldCount
-                     oneofs:(GPBMessageOneofDescription *)oneofDescriptions
-                 oneofCount:(NSUInteger)oneofCount
-                      enums:(GPBMessageEnumDescription *)enumDescriptions
-                  enumCount:(NSUInteger)enumCount
-                     ranges:(const GPBExtensionRange *)ranges
-                 rangeCount:(NSUInteger)rangeCount
-                storageSize:(size_t)storageSize
-                 wireFormat:(BOOL)wireFormat;
-+ (instancetype)
-    allocDescriptorForClass:(Class)messageClass
-                  rootClass:(Class)rootClass
-                       file:(GPBFileDescriptor *)file
-                     fields:(GPBMessageFieldDescription *)fieldDescriptions
-                 fieldCount:(NSUInteger)fieldCount
-                     oneofs:(GPBMessageOneofDescription *)oneofDescriptions
-                 oneofCount:(NSUInteger)oneofCount
-                      enums:(GPBMessageEnumDescription *)enumDescriptions
-                  enumCount:(NSUInteger)enumCount
-                     ranges:(const GPBExtensionRange *)ranges
-                 rangeCount:(NSUInteger)rangeCount
-                storageSize:(size_t)storageSize
-                 wireFormat:(BOOL)wireFormat
-        extraTextFormatInfo:(const char *)extraTextFormatInfo;
+                     fields:(void *)fieldDescriptions
+                 fieldCount:(uint32_t)fieldCount
+                storageSize:(uint32_t)storageSize
+                      flags:(GPBDescriptorInitializationFlags)flags;

 - (instancetype)initWithClass:(Class)messageClass
                         file:(GPBFileDescriptor *)file
                       fields:(NSArray *)fields
-                       oneofs:(NSArray *)oneofs
-                        enums:(NSArray *)enums
-              extensionRanges:(const GPBExtensionRange *)ranges
-         extensionRangesCount:(NSUInteger)rangeCount
-                  storageSize:(size_t)storage
+                  storageSize:(uint32_t)storage
                   wireFormat:(BOOL)wireFormat;

+// Called right after init to provide extra information to avoid init having
+// an explosion of args. These pointers are recorded, so they are expected
+// to live for the lifetime of the app.
+- (void)setupOneofs:(const char **)oneofNames
+              count:(uint32_t)count
+      firstHasIndex:(int32_t)firstHasIndex;
+- (void)setupExtraTextInfo:(const char *)extraTextFormatInfo;
+- (void)setupExtensionRanges:(const GPBExtensionRange *)ranges count:(int32_t)count;
+
@end

@interface GPBFileDescriptor ()
@ -199,14 +175,12 @@ typedef struct GPBExtensionDescription {

@interface GPBOneofDescriptor () {
 @package
-  GPBMessageOneofDescription *oneofDescription_;
+  const char *name_;
  NSArray *fields_;
-
  SEL caseSel_;
 }
- (instancetype)initWithOneofDescription:
-                    (GPBMessageOneofDescription *)oneofDescription
-                                  fields:(NSArray *)fields;
+// name must be long lived.
+- (instancetype)initWithName:(const char *)name fields:(NSArray *)fields;
@end

@interface GPBFieldDescriptor () {
@ -222,30 +196,32 @@ typedef struct GPBExtensionDescription {

 // Single initializer
 // description has to be long lived, it is held as a raw pointer.
- (instancetype)initWithFieldDescription:
-                    (GPBMessageFieldDescription *)description
-                               rootClass:(Class)rootClass
+- (instancetype)initWithFieldDescription:(void *)description
+                         includesDefault:(BOOL)includesDefault
                                  syntax:(GPBFileSyntax)syntax;
@end

@interface GPBEnumDescriptor ()
-// valueDescriptions and extraTextFormatInfo have to be long lived, they are
+// valueNames, values and extraTextFormatInfo have to be long lived, they are
 // held as raw pointers.
 + (instancetype)
    allocDescriptorForName:(NSString *)name
-                    values:(GPBMessageEnumValueDescription *)valueDescriptions
-                valueCount:(NSUInteger)valueCount
+                valueNames:(const char *)valueNames
+                    values:(const int32_t *)values
+                     count:(uint32_t)valueCount
              enumVerifier:(GPBEnumValidationFunc)enumVerifier;
 + (instancetype)
    allocDescriptorForName:(NSString *)name
-                    values:(GPBMessageEnumValueDescription *)valueDescriptions
-                valueCount:(NSUInteger)valueCount
+                valueNames:(const char *)valueNames
+                    values:(const int32_t *)values
+                     count:(uint32_t)valueCount
              enumVerifier:(GPBEnumValidationFunc)enumVerifier
       extraTextFormatInfo:(const char *)extraTextFormatInfo;

 - (instancetype)initWithName:(NSString *)name
-                      values:(GPBMessageEnumValueDescription *)valueDescriptions
-                  valueCount:(NSUInteger)valueCount
+                  valueNames:(const char *)valueNames
+                      values:(const int32_t *)values
+                       count:(uint32_t)valueCount
                enumVerifier:(GPBEnumValidationFunc)enumVerifier;
@end

@ -314,5 +290,24 @@ GPB_INLINE BOOL GPBExtensionIsWireFormat(GPBExtensionDescription *description) {
  return (description->options & GPBExtensionSetWireFormat) != 0;
 }

+// Helper for compile time assets.
+#ifndef _GPBCompileAssert
+  #if __has_feature(c_static_assert) || __has_extension(c_static_assert)
+    #define _GPBCompileAssert(test, msg) _Static_assert((test), #msg)
+  #else
+    // Pre-Xcode 7 support.
+    #define _GPBCompileAssertSymbolInner(line, msg) _GPBCompileAssert ## line ## __ ## msg
+    #define _GPBCompileAssertSymbol(line, msg) _GPBCompileAssertSymbolInner(line, msg)
+    #define _GPBCompileAssert(test, msg) \
+        typedef char _GPBCompileAssertSymbol(__LINE__, msg) [ ((test) ? 1 : -1) ]
+  #endif  // __has_feature(c_static_assert) || __has_extension(c_static_assert)
+#endif // _GPBCompileAssert
+
+// Sanity check that there isn't padding between the field description
+// structures with and without a default.
+_GPBCompileAssert(sizeof(GPBMessageFieldDescriptionWithDefault) ==
+                  (sizeof(GPBGenericValue) +
+                   sizeof(GPBMessageFieldDescription)),
+                  DescriptionsWithDefault_different_size_than_expected);

 CF_EXTERN_C_END
--- a/objectivec/GPBMessage.m
+++ b/objectivec/GPBMessage.m
@ -54,18 +54,6 @@ NSString *const GPBExceptionMessageKey =

 static NSString *const kGPBDataCoderKey = @"GPBData";

-#ifndef _GPBCompileAssert
-  #if __has_feature(c_static_assert) || __has_extension(c_static_assert)
-    #define _GPBCompileAssert(test, msg) _Static_assert((test), #msg)
-  #else
-    // Pre-Xcode 7 support.
-    #define _GPBCompileAssertSymbolInner(line, msg) _GPBCompileAssert ## line ## __ ## msg
-    #define _GPBCompileAssertSymbol(line, msg) _GPBCompileAssertSymbolInner(line, msg)
-    #define _GPBCompileAssert(test, msg) \
-        typedef char _GPBCompileAssertSymbol(__LINE__, msg) [ ((test) ? 1 : -1) ]
-  #endif  // __has_feature(c_static_assert) || __has_extension(c_static_assert)
-#endif // _GPBCompileAssert
-
 //
 // PLEASE REMEMBER:
 //
@ -789,14 +777,8 @@ static GPBUnknownFieldSet *GetOrMakeUnknownFields(GPBMessage *self) {
                                                   file:fileDescriptor
                                                 fields:NULL
                                             fieldCount:0
-                                                 oneofs:NULL
-                                             oneofCount:0
-                                                  enums:NULL
-                                              enumCount:0
-                                                 ranges:NULL
-                                             rangeCount:0
                                            storageSize:0
-                                             wireFormat:NO];
+                                                  flags:0];
  }
  return descriptor;
 }
@ -3096,7 +3078,7 @@ static void ResolveIvarSet(GPBFieldDescriptor *field,
      } else {
        GPBOneofDescriptor *oneof = field->containingOneof_;
        if (oneof && (sel == oneof->caseSel_)) {
-          int32_t index = oneof->oneofDescription_->index;
+          int32_t index = GPBFieldHasIndex(field);
          result.impToAdd = imp_implementationWithBlock(^(id obj) {
            return GPBGetHasOneof(obj, index);
          });
--- a/objectivec/GPBProtocolBuffers.m
+++ b/objectivec/GPBProtocolBuffers.m
@ -46,8 +46,6 @@
 #import "GPBWellKnownTypes.m"
 #import "GPBWireFormat.m"

-#import "google/protobuf/Descriptor.pbobjc.m"
-
 // Duration and Timestamp are #imported into GPBWellKnownTypes.m to the
 // Objective C categories added will always be linked in with the classes.
 #import "google/protobuf/Any.pbobjc.m"
--- a/objectivec/GPBRuntimeTypes.h
+++ b/objectivec/GPBRuntimeTypes.h
@ -67,7 +67,7 @@ typedef union {

 // Do not change the order of this enum (or add things to it) without thinking
 // about it very carefully. There are several things that depend on the order.
-typedef enum {
+typedef NS_ENUM(uint8_t, GPBDataType) {
  GPBDataTypeBool = 0,
  GPBDataTypeFixed32,
  GPBDataTypeSFixed32,
@ -86,7 +86,7 @@ typedef enum {
  GPBDataTypeMessage,
  GPBDataTypeGroup,
  GPBDataTypeEnum,
-} GPBDataType;
+};

 enum {
  // A count of the number of types in GPBDataType. Separated out from the
--- a/objectivec/GPBUtilities.m
+++ b/objectivec/GPBUtilities.m
@ -145,9 +145,8 @@ void GPBSetHasIvar(GPBMessage *self, int32_t idx, uint32_t fieldNumber,
 }

 void GPBMaybeClearOneof(GPBMessage *self, GPBOneofDescriptor *oneof,
-                        uint32_t fieldNumberNotToClear) {
-  int32_t hasIndex = oneof->oneofDescription_->index;
-  uint32_t fieldNumberSet = GPBGetHasOneof(self, hasIndex);
+                        int32_t oneofHasIndex, uint32_t fieldNumberNotToClear) {
+  uint32_t fieldNumberSet = GPBGetHasOneof(self, oneofHasIndex);
  if ((fieldNumberSet == fieldNumberNotToClear) || (fieldNumberSet == 0)) {
    // Do nothing/nothing set in the oneof.
    return;
@ -168,7 +167,7 @@ void GPBMaybeClearOneof(GPBMessage *self, GPBOneofDescriptor *oneof,

  // Set to nothing stored in the oneof.
  // (field number doesn't matter since setting to nothing).
-  GPBSetHasIvar(self, hasIndex, 1, NO);
+  GPBSetHasIvar(self, oneofHasIndex, 1, NO);
 }

 #pragma mark - IVar accessors
@ -200,7 +199,8 @@ void GPBMaybeClearOneof(GPBMessage *self, GPBOneofDescriptor *oneof,
 //%            NAME$S                     GPBFileSyntax syntax) {
 //%  GPBOneofDescriptor *oneof = field->containingOneof_;
 //%  if (oneof) {
-//%    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+//%    GPBMessageFieldDescription *fieldDesc = field->description_;
+//%    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
 //%  }
 //%  NSCAssert(self->messageStorage_ != NULL,
 //%            @"%@: All messages should have storage (from init)",
@ -321,7 +321,8 @@ void GPBSetRetainedObjectIvarWithFieldInternal(GPBMessage *self,
    // oneof.
    GPBOneofDescriptor *oneof = field->containingOneof_;
    if (oneof) {
-      GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+      GPBMessageFieldDescription *fieldDesc = field->description_;
+      GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
    }
    // Clear "has" if they are being set to nil.
    BOOL setHasValue = (value != nil);
@ -476,15 +477,15 @@ void GPBSetMessageRawEnumField(GPBMessage *self, GPBFieldDescriptor *field,
  GPBSetInt32IvarWithFieldInternal(self, field, value, syntax);
 }

-//%PDDM-EXPAND IVAR_POD_ACCESSORS_DEFN(Bool, BOOL)
-// This block of code is generated, do not edit it directly.
-
 BOOL GPBGetMessageBoolField(GPBMessage *self,
                            GPBFieldDescriptor *field) {
  if (GPBGetHasIvarField(self, field)) {
-    uint8_t *storage = (uint8_t *)self->messageStorage_;
-    BOOL *typePtr = (BOOL *)&storage[field->description_->offset];
-    return *typePtr;
+    // Bools are stored in the has bits to avoid needing explicit space in the
+    // storage structure.
+    // (the field number passed to the HasIvar helper doesn't really matter
+    // since the offset is never negative)
+    GPBMessageFieldDescription *fieldDesc = field->description_;
+    return GPBGetHasIvar(self, (int32_t)(fieldDesc->offset), fieldDesc->number);
  } else {
    return field.defaultValue.valueBool;
  }
@ -503,19 +504,18 @@ void GPBSetBoolIvarWithFieldInternal(GPBMessage *self,
                                     GPBFieldDescriptor *field,
                                     BOOL value,
                                     GPBFileSyntax syntax) {
+  GPBMessageFieldDescription *fieldDesc = field->description_;
  GPBOneofDescriptor *oneof = field->containingOneof_;
  if (oneof) {
-    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
  }
-  NSCAssert(self->messageStorage_ != NULL,
-            @"%@: All messages should have storage (from init)",
-            [self class]);
-#if defined(__clang_analyzer__)
-  if (self->messageStorage_ == NULL) return;
-#endif
-  uint8_t *storage = (uint8_t *)self->messageStorage_;
-  BOOL *typePtr = (BOOL *)&storage[field->description_->offset];
-  *typePtr = value;
+
+  // Bools are stored in the has bits to avoid needing explicit space in the
+  // storage structure.
+  // (the field number passed to the HasIvar helper doesn't really matter since
+  // the offset is never negative)
+  GPBSetHasIvar(self, (int32_t)(fieldDesc->offset), fieldDesc->number, value);
+
  // proto2: any value counts as having been set; proto3, it
  // has to be a non zero value.
  BOOL hasValue =
@ -553,7 +553,8 @@ void GPBSetInt32IvarWithFieldInternal(GPBMessage *self,
                                      GPBFileSyntax syntax) {
  GPBOneofDescriptor *oneof = field->containingOneof_;
  if (oneof) {
-    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+    GPBMessageFieldDescription *fieldDesc = field->description_;
+    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
  }
  NSCAssert(self->messageStorage_ != NULL,
            @"%@: All messages should have storage (from init)",
@ -601,7 +602,8 @@ void GPBSetUInt32IvarWithFieldInternal(GPBMessage *self,
                                       GPBFileSyntax syntax) {
  GPBOneofDescriptor *oneof = field->containingOneof_;
  if (oneof) {
-    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+    GPBMessageFieldDescription *fieldDesc = field->description_;
+    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
  }
  NSCAssert(self->messageStorage_ != NULL,
            @"%@: All messages should have storage (from init)",
@ -649,7 +651,8 @@ void GPBSetInt64IvarWithFieldInternal(GPBMessage *self,
                                      GPBFileSyntax syntax) {
  GPBOneofDescriptor *oneof = field->containingOneof_;
  if (oneof) {
-    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+    GPBMessageFieldDescription *fieldDesc = field->description_;
+    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
  }
  NSCAssert(self->messageStorage_ != NULL,
            @"%@: All messages should have storage (from init)",
@ -697,7 +700,8 @@ void GPBSetUInt64IvarWithFieldInternal(GPBMessage *self,
                                       GPBFileSyntax syntax) {
  GPBOneofDescriptor *oneof = field->containingOneof_;
  if (oneof) {
-    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+    GPBMessageFieldDescription *fieldDesc = field->description_;
+    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
  }
  NSCAssert(self->messageStorage_ != NULL,
            @"%@: All messages should have storage (from init)",
@ -745,7 +749,8 @@ void GPBSetFloatIvarWithFieldInternal(GPBMessage *self,
                                      GPBFileSyntax syntax) {
  GPBOneofDescriptor *oneof = field->containingOneof_;
  if (oneof) {
-    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+    GPBMessageFieldDescription *fieldDesc = field->description_;
+    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
  }
  NSCAssert(self->messageStorage_ != NULL,
            @"%@: All messages should have storage (from init)",
@ -793,7 +798,8 @@ void GPBSetDoubleIvarWithFieldInternal(GPBMessage *self,
                                       GPBFileSyntax syntax) {
  GPBOneofDescriptor *oneof = field->containingOneof_;
  if (oneof) {
-    GPBMaybeClearOneof(self, oneof, GPBFieldNumber(field));
+    GPBMessageFieldDescription *fieldDesc = field->description_;
+    GPBMaybeClearOneof(self, oneof, fieldDesc->hasIndex, fieldDesc->number);
  }
  NSCAssert(self->messageStorage_ != NULL,
            @"%@: All messages should have storage (from init)",
@ -812,7 +818,7 @@ void GPBSetDoubleIvarWithFieldInternal(GPBMessage *self,
  GPBBecomeVisibleToAutocreator(self);
 }

-//%PDDM-EXPAND-END (7 expansions)
+//%PDDM-EXPAND-END (6 expansions)

 // Aliases are function calls that are virtually the same.

--- a/objectivec/GPBUtilities_PackagePrivate.h
+++ b/objectivec/GPBUtilities_PackagePrivate.h
@ -185,7 +185,7 @@ GPB_INLINE void GPBSetHasIvarField(GPBMessage *self, GPBFieldDescriptor *field,
 }

 void GPBMaybeClearOneof(GPBMessage *self, GPBOneofDescriptor *oneof,
-                        uint32_t fieldNumberNotToClear);
+                        int32_t oneofHasIndex, uint32_t fieldNumberNotToClear);

 //%PDDM-DEFINE GPB_IVAR_SET_DECL(NAME, TYPE)
 //%void GPBSet##NAME##IvarWithFieldInternal(GPBMessage *self,
--- a/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
+++ b/objectivec/ProtocolBuffers_OSX.xcodeproj/project.pbxproj
@ -7,7 +7,6 @@
 	objects = {

 /* Begin PBXBuildFile section */
-		2CFB390415C718CE00CBF84D /* Descriptor.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = 8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */; };
 		5102DABC1891A073002037B6 /* GPBConcurrencyTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 5102DABB1891A052002037B6 /* GPBConcurrencyTests.m */; };
 		7461B5360F94FB4600A0C422 /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 1D30AB110D05D00D00671497 /* Foundation.framework */; };
 		7461B53C0F94FB4E00A0C422 /* GPBCodedInputStream.m in Sources */ = {isa = PBXBuildFile; fileRef = 7461B48F0F94F99000A0C422 /* GPBCodedInputStream.m */; };
@ -27,7 +26,6 @@
 		8B79657D14992E3F002FFBFC /* GPBRootObject.m in Sources */ = {isa = PBXBuildFile; fileRef = 8B79657914992E3E002FFBFC /* GPBRootObject.m */; };
 		8B8B615D17DF7056002EE618 /* GPBARCUnittestProtos.m in Sources */ = {isa = PBXBuildFile; fileRef = 8B8B615C17DF7056002EE618 /* GPBARCUnittestProtos.m */; settings = {COMPILER_FLAGS = "-fobjc-arc"; }; };
 		8B96157414C8C38C00A2AC0B /* GPBDescriptor.m in Sources */ = {isa = PBXBuildFile; fileRef = 8B96157314C8C38C00A2AC0B /* GPBDescriptor.m */; };
-		8B96157514CA019D00A2AC0B /* Descriptor.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = 8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */; };
 		8BBEA4A9147C727D00C4ADB7 /* GPBCodedInputStreamTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 7461B69B0F94FDF800A0C422 /* GPBCodedInputStreamTests.m */; };
 		8BBEA4AA147C727D00C4ADB7 /* GPBCodedOuputStreamTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 7461B69D0F94FDF800A0C422 /* GPBCodedOuputStreamTests.m */; };
 		8BBEA4AC147C727D00C4ADB7 /* GPBMessageTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 7461B6A30F94FDF800A0C422 /* GPBMessageTests.m */; };
@ -140,10 +138,8 @@
 		8B4248D51A92826400BC1EC6 /* Timestamp.pbobjc.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = Timestamp.pbobjc.h; path = google/protobuf/Timestamp.pbobjc.h; sourceTree = "<group>"; };
 		8B4248D61A92826400BC1EC6 /* Timestamp.pbobjc.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = Timestamp.pbobjc.m; path = google/protobuf/Timestamp.pbobjc.m; sourceTree = "<group>"; };
 		8B4248DB1A92933A00BC1EC6 /* GPBWellKnownTypesTest.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBWellKnownTypesTest.m; sourceTree = "<group>"; };
-		8B42494B1A92A16600BC1EC6 /* descriptor.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = descriptor.proto; path = ../src/google/protobuf/descriptor.proto; sourceTree = "<group>"; };
 		8B42494C1A92A16600BC1EC6 /* duration.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = duration.proto; path = ../src/google/protobuf/duration.proto; sourceTree = "<group>"; };
 		8B42494D1A92A16600BC1EC6 /* timestamp.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = timestamp.proto; path = ../src/google/protobuf/timestamp.proto; sourceTree = "<group>"; };
-		8B54585814DCC34E003D7338 /* Descriptor.pbobjc.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = Descriptor.pbobjc.h; path = google/protobuf/Descriptor.pbobjc.h; sourceTree = SOURCE_ROOT; };
 		8B79657814992E3E002FFBFC /* GPBRootObject.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GPBRootObject.h; sourceTree = "<group>"; };
 		8B79657914992E3E002FFBFC /* GPBRootObject.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBRootObject.m; sourceTree = "<group>"; };
 		8B7E6A7414893DBA00F8884A /* unittest_custom_options.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = unittest_custom_options.proto; path = ../../src/google/protobuf/unittest_custom_options.proto; sourceTree = "<group>"; };
@ -162,7 +158,6 @@
 		8BCF338814ED799900BC5317 /* GPBProtocolBuffers.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = GPBProtocolBuffers.m; sourceTree = "<group>"; };
 		8BD3981D14BE54220081D629 /* unittest_enormous_descriptor.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = unittest_enormous_descriptor.proto; path = ../../src/google/protobuf/unittest_enormous_descriptor.proto; sourceTree = "<group>"; };
 		8BD3981E14BE59D70081D629 /* GPBUnittestProtos.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBUnittestProtos.m; sourceTree = "<group>"; };
-		8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = Descriptor.pbobjc.m; path = google/protobuf/Descriptor.pbobjc.m; sourceTree = SOURCE_ROOT; };
 		8BEB5AE01498033E0078BF9D /* GPBRuntimeTypes.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBRuntimeTypes.h; sourceTree = "<group>"; };
 		F401DC2A1A8D444600FCC765 /* GPBArray.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GPBArray.h; sourceTree = "<group>"; };
 		F401DC2B1A8D444600FCC765 /* GPBArray.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBArray.m; sourceTree = "<group>"; };
@ -300,9 +295,6 @@
 				F4E675881B21D0000054530B /* Api.pbobjc.h */,
 				F4E675891B21D0000054530B /* Api.pbobjc.m */,
 				F4E675A71B21D05C0054530B /* api.proto */,
-				8B54585814DCC34E003D7338 /* Descriptor.pbobjc.h */,
-				8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */,
-				8B42494B1A92A16600BC1EC6 /* descriptor.proto */,
 				8B4248D31A92826400BC1EC6 /* Duration.pbobjc.h */,
 				8B4248D41A92826400BC1EC6 /* Duration.pbobjc.m */,
 				8B42494C1A92A16600BC1EC6 /* duration.proto */,
@ -634,7 +626,6 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				2CFB390415C718CE00CBF84D /* Descriptor.pbobjc.m in Sources */,
 				7461B53C0F94FB4E00A0C422 /* GPBCodedInputStream.m in Sources */,
 				F4E6759B1B21D0000054530B /* Empty.pbobjc.m in Sources */,
 				7461B53D0F94FB4E00A0C422 /* GPBCodedOutputStream.m in Sources */,
@ -696,7 +687,6 @@
 				8B79657D14992E3F002FFBFC /* GPBRootObject.m in Sources */,
 				8BD3981F14BE59D70081D629 /* GPBUnittestProtos.m in Sources */,
 				F4E675B11B21D0A70054530B /* FieldMask.pbobjc.m in Sources */,
-				8B96157514CA019D00A2AC0B /* Descriptor.pbobjc.m in Sources */,
 				8B8B615D17DF7056002EE618 /* GPBARCUnittestProtos.m in Sources */,
 				F4E675AF1B21D0A70054530B /* Api.pbobjc.m in Sources */,
 			);
--- a/objectivec/ProtocolBuffers_iOS.xcodeproj/project.pbxproj
+++ b/objectivec/ProtocolBuffers_iOS.xcodeproj/project.pbxproj
@ -7,7 +7,6 @@
 	objects = {

 /* Begin PBXBuildFile section */
-		2CFB390415C718CE00CBF84D /* Descriptor.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = 8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */; };
 		5102DABC1891A073002037B6 /* GPBConcurrencyTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 5102DABB1891A052002037B6 /* GPBConcurrencyTests.m */; };
 		7461B5360F94FB4600A0C422 /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 1D30AB110D05D00D00671497 /* Foundation.framework */; };
 		7461B53C0F94FB4E00A0C422 /* GPBCodedInputStream.m in Sources */ = {isa = PBXBuildFile; fileRef = 7461B48F0F94F99000A0C422 /* GPBCodedInputStream.m */; };
@ -27,7 +26,6 @@
 		8B79657D14992E3F002FFBFC /* GPBRootObject.m in Sources */ = {isa = PBXBuildFile; fileRef = 8B79657914992E3E002FFBFC /* GPBRootObject.m */; };
 		8B8B615D17DF7056002EE618 /* GPBARCUnittestProtos.m in Sources */ = {isa = PBXBuildFile; fileRef = 8B8B615C17DF7056002EE618 /* GPBARCUnittestProtos.m */; settings = {COMPILER_FLAGS = "-fobjc-arc"; }; };
 		8B96157414C8C38C00A2AC0B /* GPBDescriptor.m in Sources */ = {isa = PBXBuildFile; fileRef = 8B96157314C8C38C00A2AC0B /* GPBDescriptor.m */; };
-		8B96157514CA019D00A2AC0B /* Descriptor.pbobjc.m in Sources */ = {isa = PBXBuildFile; fileRef = 8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */; };
 		8B9742331A89D19F00DCE92C /* LaunchScreen.xib in Resources */ = {isa = PBXBuildFile; fileRef = 8B9742321A89D19F00DCE92C /* LaunchScreen.xib */; };
 		8B9742431A8AAA7800DCE92C /* CoreGraphics.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 8B9742421A8AAA7800DCE92C /* CoreGraphics.framework */; };
 		8B9A5EA61831993600A9D33B /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 1D30AB110D05D00D00671497 /* Foundation.framework */; };
@ -155,7 +153,6 @@
 		8B4248E21A929C8900BC1EC6 /* GPBWellKnownTypes.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBWellKnownTypes.m; sourceTree = "<group>"; };
 		8B4248E51A929C9900BC1EC6 /* GPBWellKnownTypesTest.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBWellKnownTypesTest.m; sourceTree = "<group>"; };
 		8B4249481A92A02300BC1EC6 /* timestamp.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = timestamp.proto; path = ../src/google/protobuf/timestamp.proto; sourceTree = "<group>"; };
-		8B4249491A92A0BA00BC1EC6 /* descriptor.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = descriptor.proto; path = ../src/google/protobuf/descriptor.proto; sourceTree = "<group>"; };
 		8B42494A1A92A0BA00BC1EC6 /* duration.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = duration.proto; path = ../src/google/protobuf/duration.proto; sourceTree = "<group>"; };
 		8B79657814992E3E002FFBFC /* GPBRootObject.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = GPBRootObject.h; sourceTree = "<group>"; };
 		8B79657914992E3E002FFBFC /* GPBRootObject.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBRootObject.m; sourceTree = "<group>"; };
@ -183,7 +180,6 @@
 		8BCF338814ED799900BC5317 /* GPBProtocolBuffers.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = GPBProtocolBuffers.m; sourceTree = "<group>"; };
 		8BD3981D14BE54220081D629 /* unittest_enormous_descriptor.proto */ = {isa = PBXFileReference; lastKnownFileType = text; name = unittest_enormous_descriptor.proto; path = ../../src/google/protobuf/unittest_enormous_descriptor.proto; sourceTree = "<group>"; };
 		8BD3981E14BE59D70081D629 /* GPBUnittestProtos.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBUnittestProtos.m; sourceTree = "<group>"; };
-		8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; name = Descriptor.pbobjc.m; path = google/protobuf/Descriptor.pbobjc.m; sourceTree = SOURCE_ROOT; };
 		8BEB5AE01498033E0078BF9D /* GPBRuntimeTypes.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GPBRuntimeTypes.h; sourceTree = "<group>"; };
 		F401DC341A8E5C6F00FCC765 /* GPBArrayTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBArrayTests.m; sourceTree = "<group>"; };
 		F41C175C1833D3310064ED4D /* GPBPerfTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GPBPerfTests.m; sourceTree = "<group>"; };
@ -224,7 +220,6 @@
 		F4E675B71B21D1440054530B /* Any.pbobjc.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; name = Any.pbobjc.m; path = google/protobuf/Any.pbobjc.m; sourceTree = "<group>"; };
 		F4E675B81B21D1440054530B /* Api.pbobjc.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = Api.pbobjc.h; path = google/protobuf/Api.pbobjc.h; sourceTree = "<group>"; };
 		F4E675B91B21D1440054530B /* Api.pbobjc.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; name = Api.pbobjc.m; path = google/protobuf/Api.pbobjc.m; sourceTree = "<group>"; };
-		F4E675BA1B21D1440054530B /* Descriptor.pbobjc.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = Descriptor.pbobjc.h; path = google/protobuf/Descriptor.pbobjc.h; sourceTree = "<group>"; };
 		F4E675BB1B21D1440054530B /* Empty.pbobjc.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = Empty.pbobjc.h; path = google/protobuf/Empty.pbobjc.h; sourceTree = "<group>"; };
 		F4E675BC1B21D1440054530B /* Empty.pbobjc.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; name = Empty.pbobjc.m; path = google/protobuf/Empty.pbobjc.m; sourceTree = "<group>"; };
 		F4E675BD1B21D1440054530B /* FieldMask.pbobjc.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = FieldMask.pbobjc.h; path = google/protobuf/FieldMask.pbobjc.h; sourceTree = "<group>"; };
@ -335,9 +330,6 @@
 				F4E675B81B21D1440054530B /* Api.pbobjc.h */,
 				F4E675B91B21D1440054530B /* Api.pbobjc.m */,
 				F4E675D91B21D1DE0054530B /* api.proto */,
-				F4E675BA1B21D1440054530B /* Descriptor.pbobjc.h */,
-				8BD3982214BE5B0C0081D629 /* Descriptor.pbobjc.m */,
-				8B4249491A92A0BA00BC1EC6 /* descriptor.proto */,
 				8B4248DD1A929C7D00BC1EC6 /* Duration.pbobjc.h */,
 				8B4248DE1A929C7D00BC1EC6 /* Duration.pbobjc.m */,
 				8B42494A1A92A0BA00BC1EC6 /* duration.proto */,
@ -722,7 +714,6 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				2CFB390415C718CE00CBF84D /* Descriptor.pbobjc.m in Sources */,
 				7461B53C0F94FB4E00A0C422 /* GPBCodedInputStream.m in Sources */,
 				F4E675D21B21D1620054530B /* Empty.pbobjc.m in Sources */,
 				F4487C731A9F906200531423 /* GPBArray.m in Sources */,
@ -792,7 +783,6 @@
 				8B79657D14992E3F002FFBFC /* GPBRootObject.m in Sources */,
 				8BD3981F14BE59D70081D629 /* GPBUnittestProtos.m in Sources */,
 				F4E675CB1B21D1610054530B /* FieldMask.pbobjc.m in Sources */,
-				8B96157514CA019D00A2AC0B /* Descriptor.pbobjc.m in Sources */,
 				8B8B615D17DF7056002EE618 /* GPBARCUnittestProtos.m in Sources */,
 				F4E675C91B21D1610054530B /* Api.pbobjc.m in Sources */,
 			);
--- a/objectivec/Tests/GPBARCUnittestProtos.m
+++ b/objectivec/Tests/GPBARCUnittestProtos.m
@ -34,6 +34,11 @@

 // Makes sure all the generated headers compile with ARC on.

+// The unittest_custom_options.proto extends the messages in descriptor.proto
+// so we build it in to test extending in general. The library doesn't provide
+// a descriptor as it doesn't use the classes/enums.
+#import "google/protobuf/Descriptor.pbobjc.h"
+
 #import "google/protobuf/Unittest.pbobjc.h"
 #import "google/protobuf/UnittestCustomOptions.pbobjc.h"
 #import "google/protobuf/UnittestCycle.pbobjc.h"
--- a/objectivec/Tests/GPBDescriptorTests.m
+++ b/objectivec/Tests/GPBDescriptorTests.m
@ -153,19 +153,6 @@
  XCTAssertFalse([fieldDescriptor isValidEnumValue:-2]);
 }

- (void)testEnumDescriptorLookup {
-  GPBDescriptor *descriptor = [TestAllTypes descriptor];
-  GPBEnumDescriptor *enumDescriptor =
-      [descriptor enumWithName:@"TestAllTypes_NestedEnum"];
-  XCTAssertNotNil(enumDescriptor);
-
-  // Descriptor cannot find foreign or imported enums.
-  enumDescriptor = [descriptor enumWithName:@"ForeignEnumEnum"];
-  XCTAssertNil(enumDescriptor);
-  enumDescriptor = [descriptor enumWithName:@"ImportEnumEnum"];
-  XCTAssertNil(enumDescriptor);
-}
-
 - (void)testOneofDescriptor {
  GPBDescriptor *descriptor = [TestOneof2 descriptor];

--- a/objectivec/Tests/GPBUnittestProtos.m
+++ b/objectivec/Tests/GPBUnittestProtos.m
@ -31,6 +31,11 @@
 // Collects all the compiled protos into one file and compiles them to make sure
 // the compiler is generating valid code.

+// The unittest_custom_options.proto extends the messages in descriptor.proto
+// so we build it in to test extending in general. The library doesn't provide
+// a descriptor as it doesn't use the classes/enums.
+#import "google/protobuf/Descriptor.pbobjc.m"
+
 #import "google/protobuf/MapProto2Unittest.pbobjc.m"
 #import "google/protobuf/MapUnittest.pbobjc.m"
 #import "google/protobuf/Unittest.pbobjc.m"
--- a/objectivec/generate_descriptors_proto.sh
+++ b/objectivec/generate_descriptors_proto.sh
@ -1,9 +1,9 @@
 #!/bin/bash

-# Run this script to regenerate descriptor.pbobjc.{h,m} after the protocol
-# compiler changes.
+# Run this script to regenerate *.pbobjc.{h,m} for the well known types after
+# the protocol compiler changes.

-# HINT:  Flags passed to generate_descriptor_proto.sh will be passed directly
+# HINT:  Flags passed to generate_well_known_types.sh will be passed directly
 #   to make when building protoc.  This is particularly useful for passing
 #   -j4 to run 4 jobs simultaneously.

@ -37,7 +37,6 @@ make $@ protoc
 declare -a RUNTIME_PROTO_FILES=( \
  google/protobuf/any.proto \
  google/protobuf/api.proto \
-  google/protobuf/descriptor.proto \
  google/protobuf/duration.proto \
  google/protobuf/empty.proto \
  google/protobuf/field_mask.proto \
--- a/objectivec/google/protobuf/Any.pbobjc.h
+++ b/objectivec/google/protobuf/Any.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Any.pbobjc.m
+++ b/objectivec/google/protobuf/Any.pbobjc.m
@ -46,47 +46,36 @@ typedef struct GPBAny__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "typeURL",
+        .dataTypeSpecific.className = NULL,
        .number = GPBAny_FieldNumber_TypeURL,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBAny__storage_, typeURL),
        .flags = GPBFieldOptional | GPBFieldTextFormatNameCustom,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBAny__storage_, typeURL),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBAny_FieldNumber_Value,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBAny__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeBytes,
-        .offset = offsetof(GPBAny__storage_, value),
-        .defaultValue.valueData = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
-#if GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
-    const char *extraTextFormatInfo = NULL;
-#else
-    static const char *extraTextFormatInfo = "\001\001\004\241!!\000";
-#endif  // GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
    GPBDescriptor *localDescriptor =
        [GPBDescriptor allocDescriptorForClass:[GPBAny class]
                                     rootClass:[GPBAnyRoot class]
                                          file:GPBAnyRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBAny__storage_)
-                                    wireFormat:NO
-                           extraTextFormatInfo:extraTextFormatInfo];
+                                         flags:0];
+#if !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
+    static const char *extraTextFormatInfo =
+        "\001\001\004\241!!\000";
+    [localDescriptor setupExtraTextInfo:extraTextFormatInfo];
+#endif  // !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/Api.pbobjc.h
+++ b/objectivec/google/protobuf/Api.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Api.pbobjc.m
+++ b/objectivec/google/protobuf/Api.pbobjc.m
@ -71,80 +71,66 @@ typedef struct GPBApi__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBApi_FieldNumber_Name,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBApi__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBApi__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "methodsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBMethod),
        .number = GPBApi_FieldNumber_MethodsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBApi__storage_, methodsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBApi__storage_, methodsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBMethod),
-        .fieldOptions = NULL,
      },
      {
        .name = "optionsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
        .number = GPBApi_FieldNumber_OptionsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBApi__storage_, optionsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBApi__storage_, optionsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
-        .fieldOptions = NULL,
      },
      {
        .name = "version",
+        .dataTypeSpecific.className = NULL,
        .number = GPBApi_FieldNumber_Version,
-        .hasIndex = 3,
+        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBApi__storage_, version),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBApi__storage_, version),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "sourceContext",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBSourceContext),
        .number = GPBApi_FieldNumber_SourceContext,
-        .hasIndex = 4,
+        .hasIndex = 2,
+        .offset = (uint32_t)offsetof(GPBApi__storage_, sourceContext),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBApi__storage_, sourceContext),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBSourceContext),
-        .fieldOptions = NULL,
      },
      {
        .name = "mixinsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBMixin),
        .number = GPBApi_FieldNumber_MixinsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBApi__storage_, mixinsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBApi__storage_, mixinsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBMixin),
-        .fieldOptions = NULL,
      },
      {
        .name = "syntax",
+        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
        .number = GPBApi_FieldNumber_Syntax,
-        .hasIndex = 6,
+        .hasIndex = 3,
+        .offset = (uint32_t)offsetof(GPBApi__storage_, syntax),
        .flags = GPBFieldOptional | GPBFieldHasEnumDescriptor,
        .dataType = GPBDataTypeEnum,
-        .offset = offsetof(GPBApi__storage_, syntax),
-        .defaultValue.valueEnum = GPBSyntax_SyntaxProto2,
-        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -152,15 +138,9 @@ typedef struct GPBApi__storage_ {
                                     rootClass:[GPBApiRoot class]
                                          file:GPBApiRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBApi__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -195,8 +175,6 @@ void SetGPBApi_Syntax_RawValue(GPBApi *message, int32_t value) {

 typedef struct GPBMethod__storage_ {
  uint32_t _has_storage_[1];
-  BOOL requestStreaming;
-  BOOL responseStreaming;
  GPBSyntax syntax;
  NSString *name;
  NSString *requestTypeURL;
@ -212,102 +190,81 @@ typedef struct GPBMethod__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBMethod_FieldNumber_Name,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBMethod__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBMethod__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "requestTypeURL",
+        .dataTypeSpecific.className = NULL,
        .number = GPBMethod_FieldNumber_RequestTypeURL,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBMethod__storage_, requestTypeURL),
        .flags = GPBFieldOptional | GPBFieldTextFormatNameCustom,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBMethod__storage_, requestTypeURL),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "requestStreaming",
+        .dataTypeSpecific.className = NULL,
        .number = GPBMethod_FieldNumber_RequestStreaming,
        .hasIndex = 2,
+        .offset = 3,  // Stored in _has_storage_ to save space.
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeBool,
-        .offset = offsetof(GPBMethod__storage_, requestStreaming),
-        .defaultValue.valueBool = NO,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "responseTypeURL",
+        .dataTypeSpecific.className = NULL,
        .number = GPBMethod_FieldNumber_ResponseTypeURL,
-        .hasIndex = 3,
+        .hasIndex = 4,
+        .offset = (uint32_t)offsetof(GPBMethod__storage_, responseTypeURL),
        .flags = GPBFieldOptional | GPBFieldTextFormatNameCustom,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBMethod__storage_, responseTypeURL),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "responseStreaming",
+        .dataTypeSpecific.className = NULL,
        .number = GPBMethod_FieldNumber_ResponseStreaming,
-        .hasIndex = 4,
+        .hasIndex = 5,
+        .offset = 6,  // Stored in _has_storage_ to save space.
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeBool,
-        .offset = offsetof(GPBMethod__storage_, responseStreaming),
-        .defaultValue.valueBool = NO,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "optionsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
        .number = GPBMethod_FieldNumber_OptionsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBMethod__storage_, optionsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBMethod__storage_, optionsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
-        .fieldOptions = NULL,
      },
      {
        .name = "syntax",
+        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
        .number = GPBMethod_FieldNumber_Syntax,
-        .hasIndex = 6,
+        .hasIndex = 7,
+        .offset = (uint32_t)offsetof(GPBMethod__storage_, syntax),
        .flags = GPBFieldOptional | GPBFieldHasEnumDescriptor,
        .dataType = GPBDataTypeEnum,
-        .offset = offsetof(GPBMethod__storage_, syntax),
-        .defaultValue.valueEnum = GPBSyntax_SyntaxProto2,
-        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
-        .fieldOptions = NULL,
      },
    };
-#if GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
-    const char *extraTextFormatInfo = NULL;
-#else
-    static const char *extraTextFormatInfo = "\002\002\007\244\241!!\000\004\010\244\241!!\000";
-#endif  // GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
    GPBDescriptor *localDescriptor =
        [GPBDescriptor allocDescriptorForClass:[GPBMethod class]
                                     rootClass:[GPBApiRoot class]
                                          file:GPBApiRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBMethod__storage_)
-                                    wireFormat:NO
-                           extraTextFormatInfo:extraTextFormatInfo];
+                                         flags:0];
+#if !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
+    static const char *extraTextFormatInfo =
+        "\002\002\007\244\241!!\000\004\010\244\241!!\000";
+    [localDescriptor setupExtraTextInfo:extraTextFormatInfo];
+#endif  // !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -349,25 +306,21 @@ typedef struct GPBMixin__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBMixin_FieldNumber_Name,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBMixin__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBMixin__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "root",
+        .dataTypeSpecific.className = NULL,
        .number = GPBMixin_FieldNumber_Root,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBMixin__storage_, root),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBMixin__storage_, root),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -375,15 +328,9 @@ typedef struct GPBMixin__storage_ {
                                     rootClass:[GPBApiRoot class]
                                          file:GPBApiRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBMixin__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/Descriptor.pbobjc.h
+++ b/objectivec/google/protobuf/Descriptor.pbobjc.h
--- a/objectivec/google/protobuf/Descriptor.pbobjc.m
+++ b/objectivec/google/protobuf/Descriptor.pbobjc.m
--- a/objectivec/google/protobuf/Duration.pbobjc.h
+++ b/objectivec/google/protobuf/Duration.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Duration.pbobjc.m
+++ b/objectivec/google/protobuf/Duration.pbobjc.m
@ -46,25 +46,21 @@ typedef struct GPBDuration__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "seconds",
+        .dataTypeSpecific.className = NULL,
        .number = GPBDuration_FieldNumber_Seconds,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBDuration__storage_, seconds),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt64,
-        .offset = offsetof(GPBDuration__storage_, seconds),
-        .defaultValue.valueInt64 = 0LL,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "nanos",
+        .dataTypeSpecific.className = NULL,
        .number = GPBDuration_FieldNumber_Nanos,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBDuration__storage_, nanos),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt32,
-        .offset = offsetof(GPBDuration__storage_, nanos),
-        .defaultValue.valueInt32 = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -72,15 +68,9 @@ typedef struct GPBDuration__storage_ {
                                     rootClass:[GPBDurationRoot class]
                                          file:GPBDurationRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBDuration__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/Empty.pbobjc.h
+++ b/objectivec/google/protobuf/Empty.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Empty.pbobjc.m
+++ b/objectivec/google/protobuf/Empty.pbobjc.m
@ -31,7 +31,7 @@ static GPBFileDescriptor *GPBEmptyRoot_FileDescriptor(void) {


 typedef struct GPBEmpty__storage_ {
-  uint32_t _has_storage_[0];
+  uint32_t _has_storage_[1];
 } GPBEmpty__storage_;

 // This method is threadsafe because it is initially called
@ -45,14 +45,8 @@ typedef struct GPBEmpty__storage_ {
                                          file:GPBEmptyRoot_FileDescriptor()
                                        fields:NULL
                                    fieldCount:0
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
                                   storageSize:sizeof(GPBEmpty__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/FieldMask.pbobjc.h
+++ b/objectivec/google/protobuf/FieldMask.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/FieldMask.pbobjc.m
+++ b/objectivec/google/protobuf/FieldMask.pbobjc.m
@ -44,14 +44,12 @@ typedef struct GPBFieldMask__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "pathsArray",
+        .dataTypeSpecific.className = NULL,
        .number = GPBFieldMask_FieldNumber_PathsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBFieldMask__storage_, pathsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBFieldMask__storage_, pathsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -59,15 +57,9 @@ typedef struct GPBFieldMask__storage_ {
                                     rootClass:[GPBFieldMaskRoot class]
                                          file:GPBFieldMaskRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBFieldMask__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/SourceContext.pbobjc.h
+++ b/objectivec/google/protobuf/SourceContext.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/SourceContext.pbobjc.m
+++ b/objectivec/google/protobuf/SourceContext.pbobjc.m
@ -44,14 +44,12 @@ typedef struct GPBSourceContext__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "fileName",
+        .dataTypeSpecific.className = NULL,
        .number = GPBSourceContext_FieldNumber_FileName,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBSourceContext__storage_, fileName),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBSourceContext__storage_, fileName),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -59,15 +57,9 @@ typedef struct GPBSourceContext__storage_ {
                                     rootClass:[GPBSourceContextRoot class]
                                          file:GPBSourceContextRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBSourceContext__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/Struct.pbobjc.h
+++ b/objectivec/google/protobuf/Struct.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Struct.pbobjc.m
+++ b/objectivec/google/protobuf/Struct.pbobjc.m
@ -30,13 +30,20 @@ static GPBFileDescriptor *GPBStructRoot_FileDescriptor(void) {
 GPBEnumDescriptor *GPBNullValue_EnumDescriptor(void) {
  static GPBEnumDescriptor *descriptor = NULL;
  if (!descriptor) {
-    static GPBMessageEnumValueDescription values[] = {
-      { .name = "NullValue", .number = GPBNullValue_NullValue },
+    static const char *valueNames =
+        "NullValue\000";
+    static const int32_t values[] = {
+        GPBNullValue_NullValue,
    };
-    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBNullValue)
-                                                   values:values
-                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)
-                                             enumVerifier:GPBNullValue_IsValidValue];
+    GPBEnumDescriptor *worker =
+        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBNullValue)
+                                       valueNames:valueNames
+                                           values:values
+                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))
+                                     enumVerifier:GPBNullValue_IsValidValue];
+    if (!OSAtomicCompareAndSwapPtrBarrier(nil, worker, (void * volatile *)&descriptor)) {
+      [worker release];
+    }
  }
  return descriptor;
 }
@ -69,14 +76,12 @@ typedef struct GPBStruct__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "fields",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBValue),
        .number = GPBStruct_FieldNumber_Fields,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBStruct__storage_, fields),
        .flags = GPBFieldMapKeyString,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBStruct__storage_, fields),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBValue),
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -84,15 +89,9 @@ typedef struct GPBStruct__storage_ {
                                     rootClass:[GPBStructRoot class]
                                          file:GPBStructRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBStruct__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -115,7 +114,6 @@ typedef struct GPBStruct__storage_ {

 typedef struct GPBValue__storage_ {
  uint32_t _has_storage_[2];
-  BOOL boolValue;
  GPBNullValue nullValue;
  NSString *stringValue;
  GPBStruct *structValue;
@ -128,78 +126,60 @@ typedef struct GPBValue__storage_ {
 + (GPBDescriptor *)descriptor {
  static GPBDescriptor *descriptor = nil;
  if (!descriptor) {
-    static GPBMessageOneofDescription oneofs[] = {
-      {
-        .name = "kind",
-        .index = -1,
-      },
-    };
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "nullValue",
+        .dataTypeSpecific.enumDescFunc = GPBNullValue_EnumDescriptor,
        .number = GPBValue_FieldNumber_NullValue,
        .hasIndex = -1,
+        .offset = (uint32_t)offsetof(GPBValue__storage_, nullValue),
        .flags = GPBFieldOptional | GPBFieldHasEnumDescriptor,
        .dataType = GPBDataTypeEnum,
-        .offset = offsetof(GPBValue__storage_, nullValue),
-        .defaultValue.valueEnum = GPBNullValue_NullValue,
-        .dataTypeSpecific.enumDescFunc = GPBNullValue_EnumDescriptor,
-        .fieldOptions = NULL,
      },
      {
        .name = "numberValue",
+        .dataTypeSpecific.className = NULL,
        .number = GPBValue_FieldNumber_NumberValue,
        .hasIndex = -1,
+        .offset = (uint32_t)offsetof(GPBValue__storage_, numberValue),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeDouble,
-        .offset = offsetof(GPBValue__storage_, numberValue),
-        .defaultValue.valueDouble = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "stringValue",
+        .dataTypeSpecific.className = NULL,
        .number = GPBValue_FieldNumber_StringValue,
        .hasIndex = -1,
+        .offset = (uint32_t)offsetof(GPBValue__storage_, stringValue),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBValue__storage_, stringValue),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "boolValue",
+        .dataTypeSpecific.className = NULL,
        .number = GPBValue_FieldNumber_BoolValue,
        .hasIndex = -1,
+        .offset = 0,  // Stored in _has_storage_ to save space.
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeBool,
-        .offset = offsetof(GPBValue__storage_, boolValue),
-        .defaultValue.valueBool = NO,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "structValue",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBStruct),
        .number = GPBValue_FieldNumber_StructValue,
        .hasIndex = -1,
+        .offset = (uint32_t)offsetof(GPBValue__storage_, structValue),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBValue__storage_, structValue),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBStruct),
-        .fieldOptions = NULL,
      },
      {
        .name = "listValue",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBListValue),
        .number = GPBValue_FieldNumber_ListValue,
        .hasIndex = -1,
+        .offset = (uint32_t)offsetof(GPBValue__storage_, listValue),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBValue__storage_, listValue),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBListValue),
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -207,15 +187,15 @@ typedef struct GPBValue__storage_ {
                                     rootClass:[GPBStructRoot class]
                                          file:GPBStructRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:oneofs
-                                    oneofCount:sizeof(oneofs) / sizeof(GPBMessageOneofDescription)
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
+    static const char *oneofs[] = {
+      "kind",
+    };
+    [localDescriptor setupOneofs:oneofs
+                           count:(uint32_t)(sizeof(oneofs) / sizeof(char*))
+                   firstHasIndex:-1];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -239,7 +219,7 @@ void SetGPBValue_NullValue_RawValue(GPBValue *message, int32_t value) {
 void GPBValue_ClearKindOneOfCase(GPBValue *message) {
  GPBDescriptor *descriptor = [message descriptor];
  GPBOneofDescriptor *oneof = descriptor->oneofs_[0];
-  GPBMaybeClearOneof(message, oneof, 0);
+  GPBMaybeClearOneof(message, oneof, -1, 0);
 }
 #pragma mark - GPBListValue

@ -260,14 +240,12 @@ typedef struct GPBListValue__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "valuesArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBValue),
        .number = GPBListValue_FieldNumber_ValuesArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBListValue__storage_, valuesArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBListValue__storage_, valuesArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBValue),
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -275,15 +253,9 @@ typedef struct GPBListValue__storage_ {
                                     rootClass:[GPBStructRoot class]
                                          file:GPBStructRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBListValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/Timestamp.pbobjc.h
+++ b/objectivec/google/protobuf/Timestamp.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Timestamp.pbobjc.m
+++ b/objectivec/google/protobuf/Timestamp.pbobjc.m
@ -46,25 +46,21 @@ typedef struct GPBTimestamp__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "seconds",
+        .dataTypeSpecific.className = NULL,
        .number = GPBTimestamp_FieldNumber_Seconds,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBTimestamp__storage_, seconds),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt64,
-        .offset = offsetof(GPBTimestamp__storage_, seconds),
-        .defaultValue.valueInt64 = 0LL,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "nanos",
+        .dataTypeSpecific.className = NULL,
        .number = GPBTimestamp_FieldNumber_Nanos,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBTimestamp__storage_, nanos),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt32,
-        .offset = offsetof(GPBTimestamp__storage_, nanos),
-        .defaultValue.valueInt32 = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -72,15 +68,9 @@ typedef struct GPBTimestamp__storage_ {
                                     rootClass:[GPBTimestampRoot class]
                                          file:GPBTimestampRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBTimestamp__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/Type.pbobjc.h
+++ b/objectivec/google/protobuf/Type.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Type.pbobjc.m
+++ b/objectivec/google/protobuf/Type.pbobjc.m
@ -45,14 +45,21 @@ static GPBFileDescriptor *GPBTypeRoot_FileDescriptor(void) {
 GPBEnumDescriptor *GPBSyntax_EnumDescriptor(void) {
  static GPBEnumDescriptor *descriptor = NULL;
  if (!descriptor) {
-    static GPBMessageEnumValueDescription values[] = {
-      { .name = "SyntaxProto2", .number = GPBSyntax_SyntaxProto2 },
-      { .name = "SyntaxProto3", .number = GPBSyntax_SyntaxProto3 },
+    static const char *valueNames =
+        "SyntaxProto2\000SyntaxProto3\000";
+    static const int32_t values[] = {
+        GPBSyntax_SyntaxProto2,
+        GPBSyntax_SyntaxProto3,
    };
-    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBSyntax)
-                                                   values:values
-                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)
-                                             enumVerifier:GPBSyntax_IsValidValue];
+    GPBEnumDescriptor *worker =
+        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBSyntax)
+                                       valueNames:valueNames
+                                           values:values
+                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))
+                                     enumVerifier:GPBSyntax_IsValidValue];
+    if (!OSAtomicCompareAndSwapPtrBarrier(nil, worker, (void * volatile *)&descriptor)) {
+      [worker release];
+    }
  }
  return descriptor;
 }
@ -96,69 +103,57 @@ typedef struct GPBType__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBType_FieldNumber_Name,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBType__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBType__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "fieldsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBField),
        .number = GPBType_FieldNumber_FieldsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBType__storage_, fieldsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBType__storage_, fieldsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBField),
-        .fieldOptions = NULL,
      },
      {
        .name = "oneofsArray",
+        .dataTypeSpecific.className = NULL,
        .number = GPBType_FieldNumber_OneofsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBType__storage_, oneofsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBType__storage_, oneofsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "optionsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
        .number = GPBType_FieldNumber_OptionsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBType__storage_, optionsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBType__storage_, optionsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
-        .fieldOptions = NULL,
      },
      {
        .name = "sourceContext",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBSourceContext),
        .number = GPBType_FieldNumber_SourceContext,
-        .hasIndex = 4,
+        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBType__storage_, sourceContext),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBType__storage_, sourceContext),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBSourceContext),
-        .fieldOptions = NULL,
      },
      {
        .name = "syntax",
+        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
        .number = GPBType_FieldNumber_Syntax,
-        .hasIndex = 5,
+        .hasIndex = 2,
+        .offset = (uint32_t)offsetof(GPBType__storage_, syntax),
        .flags = GPBFieldOptional | GPBFieldHasEnumDescriptor,
        .dataType = GPBDataTypeEnum,
-        .offset = offsetof(GPBType__storage_, syntax),
-        .defaultValue.valueEnum = GPBSyntax_SyntaxProto2,
-        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -166,15 +161,9 @@ typedef struct GPBType__storage_ {
                                     rootClass:[GPBTypeRoot class]
                                          file:GPBTypeRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBType__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -212,7 +201,6 @@ void SetGPBType_Syntax_RawValue(GPBType *message, int32_t value) {

 typedef struct GPBField__storage_ {
  uint32_t _has_storage_[1];
-  BOOL packed;
  GPBField_Kind kind;
  GPBField_Cardinality cardinality;
  int32_t number;
@ -232,139 +220,108 @@ typedef struct GPBField__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "kind",
+        .dataTypeSpecific.enumDescFunc = GPBField_Kind_EnumDescriptor,
        .number = GPBField_FieldNumber_Kind,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBField__storage_, kind),
        .flags = GPBFieldOptional | GPBFieldHasEnumDescriptor,
        .dataType = GPBDataTypeEnum,
-        .offset = offsetof(GPBField__storage_, kind),
-        .defaultValue.valueEnum = GPBField_Kind_TypeUnknown,
-        .dataTypeSpecific.enumDescFunc = GPBField_Kind_EnumDescriptor,
-        .fieldOptions = NULL,
      },
      {
        .name = "cardinality",
+        .dataTypeSpecific.enumDescFunc = GPBField_Cardinality_EnumDescriptor,
        .number = GPBField_FieldNumber_Cardinality,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBField__storage_, cardinality),
        .flags = GPBFieldOptional | GPBFieldHasEnumDescriptor,
        .dataType = GPBDataTypeEnum,
-        .offset = offsetof(GPBField__storage_, cardinality),
-        .defaultValue.valueEnum = GPBField_Cardinality_CardinalityUnknown,
-        .dataTypeSpecific.enumDescFunc = GPBField_Cardinality_EnumDescriptor,
-        .fieldOptions = NULL,
      },
      {
        .name = "number",
+        .dataTypeSpecific.className = NULL,
        .number = GPBField_FieldNumber_Number,
        .hasIndex = 2,
+        .offset = (uint32_t)offsetof(GPBField__storage_, number),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt32,
-        .offset = offsetof(GPBField__storage_, number),
-        .defaultValue.valueInt32 = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBField_FieldNumber_Name,
        .hasIndex = 3,
+        .offset = (uint32_t)offsetof(GPBField__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBField__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "typeURL",
+        .dataTypeSpecific.className = NULL,
        .number = GPBField_FieldNumber_TypeURL,
        .hasIndex = 4,
+        .offset = (uint32_t)offsetof(GPBField__storage_, typeURL),
        .flags = GPBFieldOptional | GPBFieldTextFormatNameCustom,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBField__storage_, typeURL),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "oneofIndex",
+        .dataTypeSpecific.className = NULL,
        .number = GPBField_FieldNumber_OneofIndex,
        .hasIndex = 5,
+        .offset = (uint32_t)offsetof(GPBField__storage_, oneofIndex),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt32,
-        .offset = offsetof(GPBField__storage_, oneofIndex),
-        .defaultValue.valueInt32 = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "packed",
+        .dataTypeSpecific.className = NULL,
        .number = GPBField_FieldNumber_Packed,
        .hasIndex = 6,
+        .offset = 7,  // Stored in _has_storage_ to save space.
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeBool,
-        .offset = offsetof(GPBField__storage_, packed),
-        .defaultValue.valueBool = NO,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "optionsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
        .number = GPBField_FieldNumber_OptionsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBField__storage_, optionsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBField__storage_, optionsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
-        .fieldOptions = NULL,
      },
      {
        .name = "jsonName",
+        .dataTypeSpecific.className = NULL,
        .number = GPBField_FieldNumber_JsonName,
        .hasIndex = 8,
+        .offset = (uint32_t)offsetof(GPBField__storage_, jsonName),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBField__storage_, jsonName),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "defaultValue",
+        .dataTypeSpecific.className = NULL,
        .number = GPBField_FieldNumber_DefaultValue,
        .hasIndex = 9,
+        .offset = (uint32_t)offsetof(GPBField__storage_, defaultValue),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBField__storage_, defaultValue),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
-    static GPBMessageEnumDescription enums[] = {
-      { .enumDescriptorFunc = GPBField_Kind_EnumDescriptor },
-      { .enumDescriptorFunc = GPBField_Cardinality_EnumDescriptor },
-    };
-#if GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
-    const char *extraTextFormatInfo = NULL;
-#else
-    static const char *extraTextFormatInfo = "\001\006\004\241!!\000";
-#endif  // GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
    GPBDescriptor *localDescriptor =
        [GPBDescriptor allocDescriptorForClass:[GPBField class]
                                     rootClass:[GPBTypeRoot class]
                                          file:GPBTypeRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:enums
-                                     enumCount:sizeof(enums) / sizeof(GPBMessageEnumDescription)
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBField__storage_)
-                                    wireFormat:NO
-                           extraTextFormatInfo:extraTextFormatInfo];
+                                         flags:0];
+#if !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
+    static const char *extraTextFormatInfo =
+        "\001\006\004\241!!\000";
+    [localDescriptor setupExtraTextInfo:extraTextFormatInfo];
+#endif  // !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -402,31 +359,43 @@ void SetGPBField_Cardinality_RawValue(GPBField *message, int32_t value) {
 GPBEnumDescriptor *GPBField_Kind_EnumDescriptor(void) {
  static GPBEnumDescriptor *descriptor = NULL;
  if (!descriptor) {
-    static GPBMessageEnumValueDescription values[] = {
-      { .name = "TypeUnknown", .number = GPBField_Kind_TypeUnknown },
-      { .name = "TypeDouble", .number = GPBField_Kind_TypeDouble },
-      { .name = "TypeFloat", .number = GPBField_Kind_TypeFloat },
-      { .name = "TypeInt64", .number = GPBField_Kind_TypeInt64 },
-      { .name = "TypeUint64", .number = GPBField_Kind_TypeUint64 },
-      { .name = "TypeInt32", .number = GPBField_Kind_TypeInt32 },
-      { .name = "TypeFixed64", .number = GPBField_Kind_TypeFixed64 },
-      { .name = "TypeFixed32", .number = GPBField_Kind_TypeFixed32 },
-      { .name = "TypeBool", .number = GPBField_Kind_TypeBool },
-      { .name = "TypeString", .number = GPBField_Kind_TypeString },
-      { .name = "TypeGroup", .number = GPBField_Kind_TypeGroup },
-      { .name = "TypeMessage", .number = GPBField_Kind_TypeMessage },
-      { .name = "TypeBytes", .number = GPBField_Kind_TypeBytes },
-      { .name = "TypeUint32", .number = GPBField_Kind_TypeUint32 },
-      { .name = "TypeEnum", .number = GPBField_Kind_TypeEnum },
-      { .name = "TypeSfixed32", .number = GPBField_Kind_TypeSfixed32 },
-      { .name = "TypeSfixed64", .number = GPBField_Kind_TypeSfixed64 },
-      { .name = "TypeSint32", .number = GPBField_Kind_TypeSint32 },
-      { .name = "TypeSint64", .number = GPBField_Kind_TypeSint64 },
+    static const char *valueNames =
+        "TypeUnknown\000TypeDouble\000TypeFloat\000TypeInt"
+        "64\000TypeUint64\000TypeInt32\000TypeFixed64\000Type"
+        "Fixed32\000TypeBool\000TypeString\000TypeGroup\000Ty"
+        "peMessage\000TypeBytes\000TypeUint32\000TypeEnum\000"
+        "TypeSfixed32\000TypeSfixed64\000TypeSint32\000Typ"
+        "eSint64\000";
+    static const int32_t values[] = {
+        GPBField_Kind_TypeUnknown,
+        GPBField_Kind_TypeDouble,
+        GPBField_Kind_TypeFloat,
+        GPBField_Kind_TypeInt64,
+        GPBField_Kind_TypeUint64,
+        GPBField_Kind_TypeInt32,
+        GPBField_Kind_TypeFixed64,
+        GPBField_Kind_TypeFixed32,
+        GPBField_Kind_TypeBool,
+        GPBField_Kind_TypeString,
+        GPBField_Kind_TypeGroup,
+        GPBField_Kind_TypeMessage,
+        GPBField_Kind_TypeBytes,
+        GPBField_Kind_TypeUint32,
+        GPBField_Kind_TypeEnum,
+        GPBField_Kind_TypeSfixed32,
+        GPBField_Kind_TypeSfixed64,
+        GPBField_Kind_TypeSint32,
+        GPBField_Kind_TypeSint64,
    };
-    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBField_Kind)
-                                                   values:values
-                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)
-                                             enumVerifier:GPBField_Kind_IsValidValue];
+    GPBEnumDescriptor *worker =
+        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBField_Kind)
+                                       valueNames:valueNames
+                                           values:values
+                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))
+                                     enumVerifier:GPBField_Kind_IsValidValue];
+    if (!OSAtomicCompareAndSwapPtrBarrier(nil, worker, (void * volatile *)&descriptor)) {
+      [worker release];
+    }
  }
  return descriptor;
 }
@ -463,16 +432,24 @@ BOOL GPBField_Kind_IsValidValue(int32_t value__) {
 GPBEnumDescriptor *GPBField_Cardinality_EnumDescriptor(void) {
  static GPBEnumDescriptor *descriptor = NULL;
  if (!descriptor) {
-    static GPBMessageEnumValueDescription values[] = {
-      { .name = "CardinalityUnknown", .number = GPBField_Cardinality_CardinalityUnknown },
-      { .name = "CardinalityOptional", .number = GPBField_Cardinality_CardinalityOptional },
-      { .name = "CardinalityRequired", .number = GPBField_Cardinality_CardinalityRequired },
-      { .name = "CardinalityRepeated", .number = GPBField_Cardinality_CardinalityRepeated },
+    static const char *valueNames =
+        "CardinalityUnknown\000CardinalityOptional\000C"
+        "ardinalityRequired\000CardinalityRepeated\000";
+    static const int32_t values[] = {
+        GPBField_Cardinality_CardinalityUnknown,
+        GPBField_Cardinality_CardinalityOptional,
+        GPBField_Cardinality_CardinalityRequired,
+        GPBField_Cardinality_CardinalityRepeated,
    };
-    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBField_Cardinality)
-                                                   values:values
-                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)
-                                             enumVerifier:GPBField_Cardinality_IsValidValue];
+    GPBEnumDescriptor *worker =
+        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol(GPBField_Cardinality)
+                                       valueNames:valueNames
+                                           values:values
+                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))
+                                     enumVerifier:GPBField_Cardinality_IsValidValue];
+    if (!OSAtomicCompareAndSwapPtrBarrier(nil, worker, (void * volatile *)&descriptor)) {
+      [worker release];
+    }
  }
  return descriptor;
 }
@ -516,58 +493,48 @@ typedef struct GPBEnum__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBEnum_FieldNumber_Name,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBEnum__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBEnum__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "enumvalueArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBEnumValue),
        .number = GPBEnum_FieldNumber_EnumvalueArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBEnum__storage_, enumvalueArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBEnum__storage_, enumvalueArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBEnumValue),
-        .fieldOptions = NULL,
      },
      {
        .name = "optionsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
        .number = GPBEnum_FieldNumber_OptionsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBEnum__storage_, optionsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBEnum__storage_, optionsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
-        .fieldOptions = NULL,
      },
      {
        .name = "sourceContext",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBSourceContext),
        .number = GPBEnum_FieldNumber_SourceContext,
-        .hasIndex = 3,
+        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBEnum__storage_, sourceContext),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBEnum__storage_, sourceContext),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBSourceContext),
-        .fieldOptions = NULL,
      },
      {
        .name = "syntax",
+        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
        .number = GPBEnum_FieldNumber_Syntax,
-        .hasIndex = 4,
+        .hasIndex = 2,
+        .offset = (uint32_t)offsetof(GPBEnum__storage_, syntax),
        .flags = GPBFieldOptional | GPBFieldHasEnumDescriptor,
        .dataType = GPBDataTypeEnum,
-        .offset = offsetof(GPBEnum__storage_, syntax),
-        .defaultValue.valueEnum = GPBSyntax_SyntaxProto2,
-        .dataTypeSpecific.enumDescFunc = GPBSyntax_EnumDescriptor,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -575,15 +542,9 @@ typedef struct GPBEnum__storage_ {
                                     rootClass:[GPBTypeRoot class]
                                          file:GPBTypeRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBEnum__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -627,36 +588,30 @@ typedef struct GPBEnumValue__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBEnumValue_FieldNumber_Name,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBEnumValue__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBEnumValue__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "number",
+        .dataTypeSpecific.className = NULL,
        .number = GPBEnumValue_FieldNumber_Number,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBEnumValue__storage_, number),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt32,
-        .offset = offsetof(GPBEnumValue__storage_, number),
-        .defaultValue.valueInt32 = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "optionsArray",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
        .number = GPBEnumValue_FieldNumber_OptionsArray,
        .hasIndex = GPBNoHasBit,
+        .offset = (uint32_t)offsetof(GPBEnumValue__storage_, optionsArray),
        .flags = GPBFieldRepeated,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBEnumValue__storage_, optionsArray),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBOption),
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -664,15 +619,9 @@ typedef struct GPBEnumValue__storage_ {
                                     rootClass:[GPBTypeRoot class]
                                          file:GPBTypeRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBEnumValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -702,25 +651,21 @@ typedef struct GPBOption__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "name",
+        .dataTypeSpecific.className = NULL,
        .number = GPBOption_FieldNumber_Name,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBOption__storage_, name),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBOption__storage_, name),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
      {
        .name = "value",
+        .dataTypeSpecific.className = GPBStringifySymbol(GPBAny),
        .number = GPBOption_FieldNumber_Value,
        .hasIndex = 1,
+        .offset = (uint32_t)offsetof(GPBOption__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeMessage,
-        .offset = offsetof(GPBOption__storage_, value),
-        .defaultValue.valueMessage = nil,
-        .dataTypeSpecific.className = GPBStringifySymbol(GPBAny),
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -728,15 +673,9 @@ typedef struct GPBOption__storage_ {
                                     rootClass:[GPBTypeRoot class]
                                          file:GPBTypeRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBOption__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/objectivec/google/protobuf/Wrappers.pbobjc.h
+++ b/objectivec/google/protobuf/Wrappers.pbobjc.h
@ -3,7 +3,7 @@

 #import "GPBProtocolBuffers.h"

-#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30000
+#if GOOGLE_PROTOBUF_OBJC_GEN_VERSION != 30001
 #error This file was generated by a different version of protoc which is incompatible with your Protocol Buffer library sources.
 #endif

--- a/objectivec/google/protobuf/Wrappers.pbobjc.m
+++ b/objectivec/google/protobuf/Wrappers.pbobjc.m
@ -44,14 +44,12 @@ typedef struct GPBDoubleValue__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBDoubleValue_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBDoubleValue__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeDouble,
-        .offset = offsetof(GPBDoubleValue__storage_, value),
-        .defaultValue.valueDouble = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -59,15 +57,9 @@ typedef struct GPBDoubleValue__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBDoubleValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -95,14 +87,12 @@ typedef struct GPBFloatValue__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBFloatValue_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBFloatValue__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeFloat,
-        .offset = offsetof(GPBFloatValue__storage_, value),
-        .defaultValue.valueFloat = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -110,15 +100,9 @@ typedef struct GPBFloatValue__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBFloatValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -146,14 +130,12 @@ typedef struct GPBInt64Value__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBInt64Value_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBInt64Value__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt64,
-        .offset = offsetof(GPBInt64Value__storage_, value),
-        .defaultValue.valueInt64 = 0LL,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -161,15 +143,9 @@ typedef struct GPBInt64Value__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBInt64Value__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -197,14 +173,12 @@ typedef struct GPBUInt64Value__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBUInt64Value_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBUInt64Value__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeUInt64,
-        .offset = offsetof(GPBUInt64Value__storage_, value),
-        .defaultValue.valueUInt64 = 0ULL,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -212,15 +186,9 @@ typedef struct GPBUInt64Value__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBUInt64Value__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -248,14 +216,12 @@ typedef struct GPBInt32Value__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBInt32Value_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBInt32Value__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeInt32,
-        .offset = offsetof(GPBInt32Value__storage_, value),
-        .defaultValue.valueInt32 = 0,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -263,15 +229,9 @@ typedef struct GPBInt32Value__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBInt32Value__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -299,14 +259,12 @@ typedef struct GPBUInt32Value__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBUInt32Value_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBUInt32Value__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeUInt32,
-        .offset = offsetof(GPBUInt32Value__storage_, value),
-        .defaultValue.valueUInt32 = 0U,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -314,15 +272,9 @@ typedef struct GPBUInt32Value__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBUInt32Value__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -339,7 +291,6 @@ typedef struct GPBUInt32Value__storage_ {

 typedef struct GPBBoolValue__storage_ {
  uint32_t _has_storage_[1];
-  BOOL value;
 } GPBBoolValue__storage_;

 // This method is threadsafe because it is initially called
@ -350,14 +301,12 @@ typedef struct GPBBoolValue__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBBoolValue_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = 1,  // Stored in _has_storage_ to save space.
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeBool,
-        .offset = offsetof(GPBBoolValue__storage_, value),
-        .defaultValue.valueBool = NO,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -365,15 +314,9 @@ typedef struct GPBBoolValue__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBBoolValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -401,14 +344,12 @@ typedef struct GPBStringValue__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBStringValue_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBStringValue__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeString,
-        .offset = offsetof(GPBStringValue__storage_, value),
-        .defaultValue.valueString = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -416,15 +357,9 @@ typedef struct GPBStringValue__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBStringValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
@ -452,14 +387,12 @@ typedef struct GPBBytesValue__storage_ {
    static GPBMessageFieldDescription fields[] = {
      {
        .name = "value",
+        .dataTypeSpecific.className = NULL,
        .number = GPBBytesValue_FieldNumber_Value,
        .hasIndex = 0,
+        .offset = (uint32_t)offsetof(GPBBytesValue__storage_, value),
        .flags = GPBFieldOptional,
        .dataType = GPBDataTypeBytes,
-        .offset = offsetof(GPBBytesValue__storage_, value),
-        .defaultValue.valueData = nil,
-        .dataTypeSpecific.className = NULL,
-        .fieldOptions = NULL,
      },
    };
    GPBDescriptor *localDescriptor =
@ -467,15 +400,9 @@ typedef struct GPBBytesValue__storage_ {
                                     rootClass:[GPBWrappersRoot class]
                                          file:GPBWrappersRoot_FileDescriptor()
                                        fields:fields
-                                    fieldCount:sizeof(fields) / sizeof(GPBMessageFieldDescription)
-                                        oneofs:NULL
-                                    oneofCount:0
-                                         enums:NULL
-                                     enumCount:0
-                                        ranges:NULL
-                                    rangeCount:0
+                                    fieldCount:(uint32_t)(sizeof(fields) / sizeof(GPBMessageFieldDescription))
                                   storageSize:sizeof(GPBBytesValue__storage_)
-                                    wireFormat:NO];
+                                         flags:0];
    NSAssert(descriptor == nil, @"Startup recursed!");
    descriptor = localDescriptor;
  }
--- a/src/google/protobuf/compiler/objectivec/objectivec_enum.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_enum.cc
@ -122,16 +122,6 @@ void EnumGenerator::GenerateSource(io::Printer* printer) {
      "\n",
      "name", name_);

-  printer->Print(
-      "GPBEnumDescriptor *$name$_EnumDescriptor(void) {\n"
-      "  static GPBEnumDescriptor *descriptor = NULL;\n"
-      "  if (!descriptor) {\n"
-      "    static GPBMessageEnumValueDescription values[] = {\n",
-      "name", name_);
-  printer->Indent();
-  printer->Indent();
-  printer->Indent();
-
  // Note: For the TextFormat decode info, we can't use the enum value as
  // the key because protocol buffer enums have 'allow_alias', which lets
  // a value be used more than once. Instead, the index into the list of
@ -139,41 +129,66 @@ void EnumGenerator::GenerateSource(io::Printer* printer) {
  // will be zero.
  TextFormatDecodeData text_format_decode_data;
  int enum_value_description_key = -1;
+  string text_blob;

  for (int i = 0; i < all_values_.size(); i++) {
    ++enum_value_description_key;
    string short_name(EnumValueShortName(all_values_[i]));
-    printer->Print("{ .name = \"$short_name$\", .number = $name$ },\n",
-                   "short_name", short_name,
-                   "name", EnumValueName(all_values_[i]));
+    text_blob += short_name + '\0';
    if (UnCamelCaseEnumShortName(short_name) != all_values_[i]->name()) {
      text_format_decode_data.AddString(enum_value_description_key, short_name,
                                        all_values_[i]->name());
    }
  }
-  printer->Outdent();
-  printer->Outdent();
-  printer->Outdent();
+
+  printer->Print(
+      "GPBEnumDescriptor *$name$_EnumDescriptor(void) {\n"
+      "  static GPBEnumDescriptor *descriptor = NULL;\n"
+      "  if (!descriptor) {\n",
+      "name", name_);
+
+  static const int kBytesPerLine = 40;  // allow for escaping
+  printer->Print(
+      "    static const char *valueNames =");
+  for (int i = 0; i < text_blob.size(); i += kBytesPerLine) {
+    printer->Print(
+        "\n        \"$data$\"",
+        "data", EscapeTrigraphs(CEscape(text_blob.substr(i, kBytesPerLine))));
+  }
+  printer->Print(
+      ";\n"
+      "    static const int32_t values[] = {\n");
+  for (int i = 0; i < all_values_.size(); i++) {
+    printer->Print("        $name$,\n",  "name", EnumValueName(all_values_[i]));
+  }
  printer->Print("    };\n");
+
  if (text_format_decode_data.num_entries() == 0) {
    printer->Print(
-        "    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
-        "                                                   values:values\n"
-        "                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)\n"
-        "                                             enumVerifier:$name$_IsValidValue];\n",
+        "    GPBEnumDescriptor *worker =\n"
+        "        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
+        "                                       valueNames:valueNames\n"
+        "                                           values:values\n"
+        "                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))\n"
+        "                                     enumVerifier:$name$_IsValidValue];\n",
        "name", name_);
    } else {
      printer->Print(
        "    static const char *extraTextFormatInfo = \"$extraTextFormatInfo$\";\n"
-        "    descriptor = [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
-        "                                                   values:values\n"
-        "                                               valueCount:sizeof(values) / sizeof(GPBMessageEnumValueDescription)\n"
-        "                                             enumVerifier:$name$_IsValidValue\n"
-        "                                      extraTextFormatInfo:extraTextFormatInfo];\n",
+        "    GPBEnumDescriptor *worker =\n"
+        "        [GPBEnumDescriptor allocDescriptorForName:GPBNSStringifySymbol($name$)\n"
+        "                                       valueNames:valueNames\n"
+        "                                           values:values\n"
+        "                                            count:(uint32_t)(sizeof(values) / sizeof(int32_t))\n"
+        "                                     enumVerifier:$name$_IsValidValue\n"
+        "                              extraTextFormatInfo:extraTextFormatInfo];\n",
        "name", name_,
        "extraTextFormatInfo", CEscape(text_format_decode_data.Data()));
    }
    printer->Print(
+      "    if (!OSAtomicCompareAndSwapPtrBarrier(nil, worker, (void * volatile *)&descriptor)) {\n"
+      "      [worker release];\n"
+      "    }\n"
      "  }\n"
      "  return descriptor;\n"
      "}\n\n");
--- a/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_enum_field.cc
@ -59,6 +59,9 @@ void SetEnumVariables(const FieldDescriptor* descriptor,
  (*variables)["enum_verifier"] = type + "_IsValidValue";
  (*variables)["enum_desc_func"] = type + "_EnumDescriptor";

+  (*variables)["dataTypeSpecific_name"] = "enumDescFunc";
+  (*variables)["dataTypeSpecific_value"] = (*variables)["enum_desc_func"];
+
  const Descriptor* msg_descriptor = descriptor->containing_type();
  (*variables)["owning_message_class"] = ClassName(msg_descriptor);
 }
@ -72,13 +75,6 @@ EnumFieldGenerator::EnumFieldGenerator(const FieldDescriptor* descriptor,

 EnumFieldGenerator::~EnumFieldGenerator() {}

-void EnumFieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "  .dataTypeSpecific.enumDescFunc = $enum_desc_func$,\n");
-}
-
 void EnumFieldGenerator::GenerateCFunctionDeclarations(
    io::Printer* printer) const {
  if (!HasPreservingUnknownEnumSemantics(descriptor_->file())) {
@ -145,13 +141,6 @@ void RepeatedEnumFieldGenerator::FinishInitialization(void) {
      "// |" + variables_["name"] + "| contains |" + variables_["storage_type"] + "|\n";
 }

-void RepeatedEnumFieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "  .dataTypeSpecific.enumDescFunc = $enum_desc_func$,\n");
-}
-
 }  // namespace objectivec
 }  // namespace compiler
 }  // namespace protobuf
--- a/src/google/protobuf/compiler/objectivec/objectivec_enum_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_enum_field.h
@ -45,7 +45,6 @@ class EnumFieldGenerator : public SingleFieldGenerator {
                                              const Options& options);

 public:
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;
  virtual void GenerateCFunctionDeclarations(io::Printer* printer) const;
  virtual void GenerateCFunctionImplementations(io::Printer* printer) const;
  virtual void DetermineForwardDeclarations(set<string>* fwd_decls) const;
@ -64,7 +63,6 @@ class RepeatedEnumFieldGenerator : public RepeatedFieldGenerator {

 public:
  virtual void FinishInitialization();
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;

 protected:
  RepeatedEnumFieldGenerator(const FieldDescriptor* descriptor,
--- a/src/google/protobuf/compiler/objectivec/objectivec_extension.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_extension.cc
@ -114,14 +114,14 @@ void ExtensionGenerator::GenerateStaticVariablesInitialization(

  printer->Print(vars,
                 "{\n"
-                 "  .singletonName = GPBStringifySymbol($root_class_and_method_name$),\n"
-                 "  .dataType = $extension_type$,\n"
-                 "  .extendedClass = GPBStringifySymbol($extended_type$),\n"
-                 "  .fieldNumber = $number$,\n"
                 "  .defaultValue.$default_name$ = $default$,\n"
+                 "  .singletonName = GPBStringifySymbol($root_class_and_method_name$),\n"
+                 "  .extendedClass = GPBStringifySymbol($extended_type$),\n"
                 "  .messageOrGroupClassName = $type$,\n"
-                 "  .options = $options$,\n"
                 "  .enumDescriptorFunc = $enum_desc_func_name$,\n"
+                 "  .fieldNumber = $number$,\n"
+                 "  .dataType = $extension_type$,\n"
+                 "  .options = $options$,\n"
                 "},\n");
 }

--- a/src/google/protobuf/compiler/objectivec/objectivec_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_field.cc
@ -28,6 +28,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+#include <iostream>
+
 #include <google/protobuf/compiler/objectivec/objectivec_field.h>
 #include <google/protobuf/compiler/objectivec/objectivec_helpers.h>
 #include <google/protobuf/compiler/objectivec/objectivec_enum_field.h>
@ -75,7 +77,6 @@ void SetCommonFieldVariables(const FieldDescriptor* descriptor,
  (*variables)["field_number_name"] =
      classname + "_FieldNumber_" + capitalized_name;
  (*variables)["field_number"] = SimpleItoa(descriptor->number());
-  (*variables)["has_index"] = SimpleItoa(descriptor->index());
  (*variables)["field_type"] = GetCapitalizedType(descriptor);
  std::vector<string> field_flags;
  if (descriptor->is_repeated()) field_flags.push_back("GPBFieldRepeated");
@ -99,18 +100,9 @@ void SetCommonFieldVariables(const FieldDescriptor* descriptor,
  (*variables)["dataTypeSpecific_name"] = "className";
  (*variables)["dataTypeSpecific_value"] = "NULL";

-  string field_options = descriptor->options().SerializeAsString();
-  // Must convert to a standard byte order for packing length into
-  // a cstring.
-  uint32 length = ghtonl(field_options.length());
-  if (length > 0) {
-    string bytes((const char*)&length, sizeof(length));
-    bytes.append(field_options);
-    string options_str = "\"" + CEscape(bytes) + "\"";
-    (*variables)["fieldoptions"] = "\"" + CEscape(bytes) + "\"";
-  } else {
-    (*variables)["fieldoptions"] = "";
-  }
+  (*variables)["storage_offset_value"] =
+      "(uint32_t)offsetof(" + classname + "__storage_, " + camel_case_name + ")";
+  (*variables)["storage_offset_comment"] = "";

  // Clear some common things so they can be set just when needed.
  (*variables)["storage_attribute"] = "";
@ -190,52 +182,54 @@ void FieldGenerator::DetermineForwardDeclarations(
 }

 void FieldGenerator::GenerateFieldDescription(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "{\n"
-      "  .name = \"$name$\",\n"
-      "  .number = $field_number_name$,\n"
-      "  .hasIndex = $has_index$,\n"
-      "  .flags = $fieldflags$,\n"
-      "  .dataType = GPBDataType$field_type$,\n"
-      "  .offset = offsetof($classname$__storage_, $name$),\n"
-      "  .defaultValue.$default_name$ = $default$,\n");
-
-  // TODO(thomasvl): It might be useful to add a CPP wrapper to support
-  // compiling away the EnumDescriptors.  To do that, we'd need a #if here
-  // to control setting the descriptor vs. the validator, and above in
-  // SetCommonFieldVariables() we'd want to wrap how we add
-  // GPBFieldHasDefaultValue to the flags.
-
-  // "  .dataTypeSpecific.value* = [something],"
-  GenerateFieldDescriptionTypeSpecific(printer);
-
-  const string& field_options(variables_.find("fieldoptions")->second);
-  if (field_options.empty()) {
-    printer->Print("  .fieldOptions = NULL,\n");
-  } else {
-    // Can't use PrintRaw() here to get the #if/#else/#endif lines completely
-    // outdented because the need for indent captured on the previous
-    // printing of a \n and there is no way to get the current indent level
-    // to call the right number of Outdent()/Indents() to maintain state.
+    io::Printer* printer, bool include_default) const {
+  // Printed in the same order as the structure decl.
+  if (include_default) {
    printer->Print(
        variables_,
-        "#if GPBOBJC_INCLUDE_FIELD_OPTIONS\n"
-        "  .fieldOptions = $fieldoptions$,\n"
-        "#else\n"
-        "  .fieldOptions = NULL,\n"
-        "#endif  // GPBOBJC_INCLUDE_FIELD_OPTIONS\n");
+        "{\n"
+        "  .defaultValue.$default_name$ = $default$,\n"
+        "  .core.name = \"$name$\",\n"
+        "  .core.dataTypeSpecific.$dataTypeSpecific_name$ = $dataTypeSpecific_value$,\n"
+        "  .core.number = $field_number_name$,\n"
+        "  .core.hasIndex = $has_index$,\n"
+        "  .core.offset = $storage_offset_value$,$storage_offset_comment$\n"
+        "  .core.flags = $fieldflags$,\n"
+        "  .core.dataType = GPBDataType$field_type$,\n"
+        "},\n");
+  } else {
+    printer->Print(
+        variables_,
+        "{\n"
+        "  .name = \"$name$\",\n"
+        "  .dataTypeSpecific.$dataTypeSpecific_name$ = $dataTypeSpecific_value$,\n"
+        "  .number = $field_number_name$,\n"
+        "  .hasIndex = $has_index$,\n"
+        "  .offset = $storage_offset_value$,$storage_offset_comment$\n"
+        "  .flags = $fieldflags$,\n"
+        "  .dataType = GPBDataType$field_type$,\n"
+        "},\n");
  }
-
-  printer->Print("},\n");
 }

-void FieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  printer->Print(
-      variables_,
-      "  .dataTypeSpecific.$dataTypeSpecific_name$ = $dataTypeSpecific_value$,\n");
+void FieldGenerator::SetRuntimeHasBit(int has_index) {
+  variables_["has_index"] = SimpleItoa(has_index);
+}
+
+void FieldGenerator::SetNoHasBit(void) {
+  variables_["has_index"] = "GPBNoHasBit";
+}
+
+int FieldGenerator::ExtraRuntimeHasBitsNeeded(void) const {
+  return 0;
+}
+
+void FieldGenerator::SetExtraRuntimeHasBitsBase(int index_base) {
+  // NOTE: src/google/protobuf/compiler/plugin.cc makes use of cerr for some
+  // error cases, so it seems to be ok to use as a back door for errors.
+  cerr << "Error: should have overriden SetExtraRuntimeHasBitsBase()." << endl;
+  cerr.flush();
+  abort();
 }

 void FieldGenerator::SetOneofIndexBase(int index_base) {
@ -302,6 +296,14 @@ bool SingleFieldGenerator::WantsHasProperty(void) const {
  return false;
 }

+bool SingleFieldGenerator::RuntimeUsesHasBit(void) const {
+  if (descriptor_->containing_oneof() != NULL) {
+    // The oneof tracks what is set instead.
+    return false;
+  }
+  return true;
+}
+
 ObjCObjFieldGenerator::ObjCObjFieldGenerator(const FieldDescriptor* descriptor,
                                             const Options& options)
    : SingleFieldGenerator(descriptor, options) {
@ -347,8 +349,6 @@ void ObjCObjFieldGenerator::GeneratePropertyDeclaration(
 RepeatedFieldGenerator::RepeatedFieldGenerator(
    const FieldDescriptor* descriptor, const Options& options)
    : ObjCObjFieldGenerator(descriptor, options) {
-  // Repeated fields don't use the has index.
-  variables_["has_index"] = "GPBNoHasBit";
  // Default to no comment and let the cases needing it fill it in.
  variables_["array_comment"] = "";
 }
@ -402,6 +402,10 @@ bool RepeatedFieldGenerator::WantsHasProperty(void) const {
  return false;
 }

+bool RepeatedFieldGenerator::RuntimeUsesHasBit(void) const {
+  return false;  // The array having anything is what is used.
+}
+
 FieldGeneratorMap::FieldGeneratorMap(const Descriptor* descriptor,
                                     const Options& options)
    : descriptor_(descriptor),
@ -432,12 +436,40 @@ const FieldGenerator& FieldGeneratorMap::get_extension(int index) const {
  return *extension_generators_[index];
 }

+int FieldGeneratorMap::CalculateHasBits(void) {
+  int total_bits = 0;
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    if (field_generators_[i]->RuntimeUsesHasBit()) {
+      field_generators_[i]->SetRuntimeHasBit(total_bits);
+      ++total_bits;
+    } else {
+      field_generators_[i]->SetNoHasBit();
+    }
+    int extra_bits = field_generators_[i]->ExtraRuntimeHasBitsNeeded();
+    if (extra_bits) {
+      field_generators_[i]->SetExtraRuntimeHasBitsBase(total_bits);
+      total_bits += extra_bits;
+    }
+  }
+  return total_bits;
+}
+
 void FieldGeneratorMap::SetOneofIndexBase(int index_base) {
  for (int i = 0; i < descriptor_->field_count(); i++) {
    field_generators_[i]->SetOneofIndexBase(index_base);
  }
 }

+bool FieldGeneratorMap::DoesAnyFieldHaveNonZeroDefault(void) const {
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    if (HasNonZeroDefaultValue(descriptor_->field(i))) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 }  // namespace objectivec
 }  // namespace compiler
 }  // namespace protobuf
--- a/src/google/protobuf/compiler/objectivec/objectivec_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_field.h
@ -61,7 +61,6 @@ class FieldGenerator {

  // Called by GenerateFieldDescription, exposed for classes that need custom
  // generation.
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;

  // Exposed for subclasses to extend, base does nothing.
  virtual void GenerateCFunctionDeclarations(io::Printer* printer) const;
@ -71,9 +70,16 @@ class FieldGenerator {
  virtual void DetermineForwardDeclarations(set<string>* fwd_decls) const;

  // Used during generation, not intended to be extended by subclasses.
-  void GenerateFieldDescription(io::Printer* printer) const;
+  void GenerateFieldDescription(
+      io::Printer* printer, bool include_default) const;
  void GenerateFieldNumberConstant(io::Printer* printer) const;

+  // Exposed to get and set the has bits information.
+  virtual bool RuntimeUsesHasBit(void) const = 0;
+  void SetRuntimeHasBit(int has_index);
+  void SetNoHasBit(void);
+  virtual int ExtraRuntimeHasBitsNeeded(void) const;
+  virtual void SetExtraRuntimeHasBitsBase(int index_base);
  void SetOneofIndexBase(int index_base);

  string variable(const char* key) const {
@ -109,6 +115,8 @@ class SingleFieldGenerator : public FieldGenerator {

  virtual void GeneratePropertyImplementation(io::Printer* printer) const;

+  virtual bool RuntimeUsesHasBit(void) const;
+
 protected:
  SingleFieldGenerator(const FieldDescriptor* descriptor,
                       const Options& options);
@ -143,6 +151,8 @@ class RepeatedFieldGenerator : public ObjCObjFieldGenerator {

  virtual void GeneratePropertyImplementation(io::Printer* printer) const;

+  virtual bool RuntimeUsesHasBit(void) const;
+
 protected:
  RepeatedFieldGenerator(const FieldDescriptor* descriptor,
                         const Options& options);
@ -162,8 +172,14 @@ class FieldGeneratorMap {
  const FieldGenerator& get(const FieldDescriptor* field) const;
  const FieldGenerator& get_extension(int index) const;

+  // Assigns the has bits and returns the number of bits needed.
+  int CalculateHasBits(void);
+
  void SetOneofIndexBase(int index_base);

+  // Check if any field of this message has a non zero default.
+  bool DoesAnyFieldHaveNonZeroDefault(void) const;
+
 private:
  const Descriptor* descriptor_;
  scoped_array<scoped_ptr<FieldGenerator> > field_generators_;
--- a/src/google/protobuf/compiler/objectivec/objectivec_file.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_file.cc
@ -45,7 +45,7 @@ namespace protobuf {
 // This is also found in GPBBootstrap.h, and needs to be kept in sync.  It
 // is the version check done to ensure generated code works with the current
 // runtime being used.
-const int32 GOOGLE_PROTOBUF_OBJC_GEN_VERSION = 30000;
+const int32 GOOGLE_PROTOBUF_OBJC_GEN_VERSION = 30001;

 namespace compiler {
 namespace objectivec {
--- a/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_helpers.cc
@ -220,11 +220,6 @@ string NameFromFieldDescriptor(const FieldDescriptor* field) {
  }
 }

-// Escape C++ trigraphs by escaping question marks to \?
-string EscapeTrigraphs(const string& to_escape) {
-  return StringReplace(to_escape, "?", "\\?", true);
-}
-
 void PathSplit(const string& path, string* directory, string* basename) {
  string::size_type last_slash = path.rfind('/');
  if (last_slash == string::npos) {
@ -264,6 +259,11 @@ bool IsSpecialName(const string& name, const string* special_names,

 }  // namespace

+// Escape C++ trigraphs by escaping question marks to \?
+string EscapeTrigraphs(const string& to_escape) {
+  return StringReplace(to_escape, "?", "\\?", true);
+}
+
 string StripProto(const string& filename) {
  if (HasSuffixString(filename, ".protodevel")) {
    return StripSuffixString(filename, ".protodevel");
@ -734,7 +734,7 @@ string DefaultValue(const FieldDescriptor* field) {
        uint32 length = ghtonl(default_string.length());
        string bytes((const char*)&length, sizeof(length));
        bytes.append(default_string);
-        return "(NSData*)\"" + CEscape(bytes) + "\"";
+        return "(NSData*)\"" + EscapeTrigraphs(CEscape(bytes)) + "\"";
      } else {
        return "@\"" + EscapeTrigraphs(CEscape(default_string)) + "\"";
      }
@ -751,6 +751,50 @@ string DefaultValue(const FieldDescriptor* field) {
  return NULL;
 }

+bool HasNonZeroDefaultValue(const FieldDescriptor* field) {
+  // Repeated fields don't have defaults.
+  if (field->is_repeated()) {
+    return false;
+  }
+
+  if (!field->has_default_value()) {
+    // No custom default set in the proto file.
+    return false;
+  }
+
+  // Some proto file set the default to the zero value, so make sure the value
+  // isn't the zero case.
+  switch (field->cpp_type()) {
+    case FieldDescriptor::CPPTYPE_INT32:
+      return field->default_value_int32() != 0;
+    case FieldDescriptor::CPPTYPE_UINT32:
+      return field->default_value_uint32() != 0U;
+    case FieldDescriptor::CPPTYPE_INT64:
+      return field->default_value_int64() != 0LL;
+    case FieldDescriptor::CPPTYPE_UINT64:
+      return field->default_value_uint64() != 0ULL;
+    case FieldDescriptor::CPPTYPE_DOUBLE:
+      return field->default_value_double() != 0.0;
+    case FieldDescriptor::CPPTYPE_FLOAT:
+      return field->default_value_float() != 0.0f;
+    case FieldDescriptor::CPPTYPE_BOOL:
+      return field->default_value_bool();
+    case FieldDescriptor::CPPTYPE_STRING: {
+      const string& default_string = field->default_value_string();
+      return default_string.length() != 0;
+    }
+    case FieldDescriptor::CPPTYPE_ENUM:
+      return field->default_value_enum()->number() != 0;
+    case FieldDescriptor::CPPTYPE_MESSAGE:
+      return false;
+  }
+
+  // Some compilers report reaching end of function even though all cases of
+  // the enum are handed in the switch.
+  GOOGLE_LOG(FATAL) << "Can't get here.";
+  return false;
+}
+
 string BuildFlagsString(const vector<string>& strings) {
  if (strings.size() == 0) {
    return "0";
--- a/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_helpers.h
@ -48,6 +48,9 @@ struct Options {
  string expected_prefixes_path;
 };

+// Escape C++ trigraphs by escaping question marks to "\?".
+string EscapeTrigraphs(const string& to_escape);
+
 // Strips ".proto" or ".protodevel" from the end of a filename.
 string StripProto(const string& filename);

@ -143,6 +146,7 @@ bool IsReferenceType(const FieldDescriptor* field);

 string GPBGenericValueFieldName(const FieldDescriptor* field);
 string DefaultValue(const FieldDescriptor* field);
+bool HasNonZeroDefaultValue(const FieldDescriptor* field);

 string BuildFlagsString(const vector<string>& strings);

--- a/src/google/protobuf/compiler/objectivec/objectivec_map_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_map_field.cc
@ -140,13 +140,18 @@ MapFieldGenerator::MapFieldGenerator(const FieldDescriptor* descriptor,
          value_field_generator_->variable("storage_type") + "*>";
    }
  }
+
+  variables_["dataTypeSpecific_name"] =
+      value_field_generator_->variable("dataTypeSpecific_name");
+  variables_["dataTypeSpecific_value"] =
+      value_field_generator_->variable("dataTypeSpecific_value");
 }

 MapFieldGenerator::~MapFieldGenerator() {}

 void MapFieldGenerator::FinishInitialization(void) {
  RepeatedFieldGenerator::FinishInitialization();
-  // Use the array_comment suport in RepeatedFieldGenerator to output what the
+  // Use the array_comment support in RepeatedFieldGenerator to output what the
  // values in the map are.
  const FieldDescriptor* value_descriptor =
      descriptor_->message_type()->FindFieldByName("value");
@ -156,13 +161,6 @@ void MapFieldGenerator::FinishInitialization(void) {
  }
 }

-void MapFieldGenerator::GenerateFieldDescriptionTypeSpecific(
-    io::Printer* printer) const {
-  // Relay it to the value generator to provide enum validator, message
-  // class, etc.
-  value_field_generator_->GenerateFieldDescriptionTypeSpecific(printer);
-}
-
 void MapFieldGenerator::DetermineForwardDeclarations(
    set<string>* fwd_decls) const {
  RepeatedFieldGenerator::DetermineForwardDeclarations(fwd_decls);
--- a/src/google/protobuf/compiler/objectivec/objectivec_map_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_map_field.h
@ -46,7 +46,6 @@ class MapFieldGenerator : public RepeatedFieldGenerator {

 public:
  virtual void FinishInitialization(void);
-  virtual void GenerateFieldDescriptionTypeSpecific(io::Printer* printer) const;

 protected:
  MapFieldGenerator(const FieldDescriptor* descriptor, const Options& options);
--- a/src/google/protobuf/compiler/objectivec/objectivec_message.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_message.cc
@ -66,11 +66,12 @@ int OrderGroupForFieldDescriptor(const FieldDescriptor* descriptor) {
  // The first item in the object structure is our uint32[] for has bits.
  // We then want to order things to make the instances as small as
  // possible. So we follow the has bits with:
-  //   1. Bools (1 byte)
-  //   2. Anything always 4 bytes - float, *32, enums
-  //   3. Anything that is always a pointer (they will be 8 bytes on 64 bit
+  //   1. Anything always 4 bytes - float, *32, enums
+  //   2. Anything that is always a pointer (they will be 8 bytes on 64 bit
  //      builds and 4 bytes on 32bit builds.
-  //   4. Anything always 8 bytes - double, *64
+  //   3. Anything always 8 bytes - double, *64
+  //
+  // NOTE: Bools aren't listed, they were stored in the has bits.
  //
  // Why? Using 64bit builds as an example, this means worse case, we have
  // enough bools that we overflow 1 byte from 4 byte alignment, so 3 bytes
@ -115,9 +116,9 @@ int OrderGroupForFieldDescriptor(const FieldDescriptor* descriptor) {
    case FieldDescriptor::TYPE_ENUM:
      return 2;

-    // 1 byte.
+    // 0 bytes. Stored in the has bits.
    case FieldDescriptor::TYPE_BOOL:
-      return 1;
+      return 99;  // End of the list (doesn't really matter).
  }

  // Some compilers report reaching end of function even though all cases of
@ -404,32 +405,28 @@ void MessageGenerator::GenerateSource(io::Printer* printer) {
    sort(sorted_extensions.begin(), sorted_extensions.end(),
         ExtensionRangeOrdering());

-    // TODO(thomasvl): Finish optimizing has bit. The current behavior is as
-    // follows:
-    // 1. objectivec_field.cc's SetCommonFieldVariables() defaults the has_index
-    //    to the field's index in the list of fields.
-    // 2. RepeatedFieldGenerator::RepeatedFieldGenerator() sets has_index to
-    //    GPBNoHasBit because repeated fields & map<> fields don't use the has
-    //    bit.
-    // 3. FieldGenerator::SetOneofIndexBase() overrides has_bit with a negative
-    //    index that groups all the elements on of the oneof.
-    // So in has_storage, we need enough bits for the single fields that aren't
-    // in any oneof, and then one int32 for each oneof (to store the field
-    // number).  So we could save a little space by not using the field's index
-    // and instead make a second pass only assigning indexes for the fields
-    // that would need it.  The only savings would come when messages have over
-    // a multiple of 32 fields with some number being repeated or in oneofs to
-    // drop the count below that 32 multiple; so it hasn't seemed worth doing
-    // at the moment.
-    size_t num_has_bits = descriptor_->field_count();
+    // Assign has bits:
+    // 1. FieldGeneratorMap::CalculateHasBits() loops through the fields seeing
+    //    who needs has bits and assigning them.
+    // 2. FieldGenerator::SetOneofIndexBase() overrides has_bit with a negative
+    //    index that groups all the elements in the oneof.
+    size_t num_has_bits = field_generators_.CalculateHasBits();
    size_t sizeof_has_storage = (num_has_bits + 31) / 32;
+    if (sizeof_has_storage == 0) {
+      // In the case where no field needs has bits, don't let the _has_storage_
+      // end up as zero length (zero length arrays are sort of a grey area
+      // since it has to be at the start of the struct). This also ensures a
+      // field with only oneofs keeps the required negative indices they need.
+      sizeof_has_storage = 1;
+    }
    // Tell all the fields the oneof base.
    for (vector<OneofGenerator*>::iterator iter = oneof_generators_.begin();
         iter != oneof_generators_.end(); ++iter) {
      (*iter)->SetOneofIndexBase(sizeof_has_storage);
    }
    field_generators_.SetOneofIndexBase(sizeof_has_storage);
-    // Add an int32 for each oneof to store which is set.
+    // sizeof_has_storage needs enough bits for the single fields that aren't in
+    // any oneof, and then one int32 for each oneof (to store the field number).
    sizeof_has_storage += descriptor_->oneof_decl_count();

    printer->Print(
@ -456,47 +453,26 @@ void MessageGenerator::GenerateSource(io::Printer* printer) {
        "  static GPBDescriptor *descriptor = nil;\n"
        "  if (!descriptor) {\n");

-    bool has_oneofs = oneof_generators_.size();
-    if (has_oneofs) {
-      printer->Print(
-          "    static GPBMessageOneofDescription oneofs[] = {\n");
-      printer->Indent();
-      printer->Indent();
-      printer->Indent();
-      for (vector<OneofGenerator*>::iterator iter = oneof_generators_.begin();
-           iter != oneof_generators_.end(); ++iter) {
-        (*iter)->GenerateDescription(printer);
-      }
-      printer->Outdent();
-      printer->Outdent();
-      printer->Outdent();
-      printer->Print(
-          "    };\n");
-    }
-
    TextFormatDecodeData text_format_decode_data;
    bool has_fields = descriptor_->field_count() > 0;
+    bool need_defaults = field_generators_.DoesAnyFieldHaveNonZeroDefault();
+    string field_description_type;
+    if (need_defaults) {
+      field_description_type = "GPBMessageFieldDescriptionWithDefault";
+    } else {
+      field_description_type = "GPBMessageFieldDescription";
+    }
    if (has_fields) {
-      // TODO(thomasvl): The plugin's FieldGenerator::GenerateFieldDescription()
-      // wraps the fieldOptions's value of this structure in an CPP gate so
-      // they can be compiled away; but that still results in a const char* in
-      // the structure for a NULL pointer for every message field.  If the
-      // fieldOptions are moved to a separate payload like the TextFormat extra
-      // data is, then it would shrink that static data shrinking the binaries
-      // a little more.
-      // TODO(thomasvl): proto3 syntax doens't need a defaultValue in the
-      // structure because primitive types are always zero.  If we add a second
-      // structure and a different initializer, we can avoid the wasted static
-      // storage for every field in a proto3 message.
      printer->Print(
-          "    static GPBMessageFieldDescription fields[] = {\n");
+          "    static $field_description_type$ fields[] = {\n",
+          "field_description_type", field_description_type);
      printer->Indent();
      printer->Indent();
      printer->Indent();
      for (int i = 0; i < descriptor_->field_count(); ++i) {
        const FieldGenerator& field_generator =
            field_generators_.get(sorted_fields[i]);
-        field_generator.GenerateFieldDescription(printer);
+        field_generator.GenerateFieldDescription(printer, need_defaults);
        if (field_generator.needs_textformat_name_support()) {
          text_format_decode_data.AddString(sorted_fields[i]->number(),
                                            field_generator.generated_objc_name(),
@ -510,111 +486,89 @@ void MessageGenerator::GenerateSource(io::Printer* printer) {
          "    };\n");
    }

-    bool has_enums = enum_generators_.size();
-    if (has_enums) {
-      printer->Print(
-          "    static GPBMessageEnumDescription enums[] = {\n");
-      printer->Indent();
-      printer->Indent();
-      printer->Indent();
-      for (vector<EnumGenerator*>::iterator iter = enum_generators_.begin();
-           iter != enum_generators_.end(); ++iter) {
-        printer->Print("{ .enumDescriptorFunc = $name$_EnumDescriptor },\n",
-                       "name", (*iter)->name());
-      }
-      printer->Outdent();
-      printer->Outdent();
-      printer->Outdent();
-      printer->Print(
-          "    };\n");
-    }
-
-    bool has_extensions = sorted_extensions.size();
-    if (has_extensions) {
-      printer->Print(
-          "    static GPBExtensionRange ranges[] = {\n");
-      printer->Indent();
-      printer->Indent();
-      printer->Indent();
-      for (int i = 0; i < sorted_extensions.size(); i++) {
-        printer->Print("{ .start = $start$, .end = $end$ },\n",
-                       "start", SimpleItoa(sorted_extensions[i]->start),
-                       "end", SimpleItoa(sorted_extensions[i]->end));
-      }
-      printer->Outdent();
-      printer->Outdent();
-      printer->Outdent();
-      printer->Print(
-          "    };\n");
-    }
-
    map<string, string> vars;
    vars["classname"] = class_name_;
    vars["rootclassname"] = root_classname_;
    vars["fields"] = has_fields ? "fields" : "NULL";
-    vars["fields_count"] =
-        has_fields ? "sizeof(fields) / sizeof(GPBMessageFieldDescription)" : "0";
-    vars["oneofs"] = has_oneofs ? "oneofs" : "NULL";
-    vars["oneof_count"] =
-        has_oneofs ? "sizeof(oneofs) / sizeof(GPBMessageOneofDescription)" : "0";
-    vars["enums"] = has_enums ? "enums" : "NULL";
-    vars["enum_count"] =
-        has_enums ? "sizeof(enums) / sizeof(GPBMessageEnumDescription)" : "0";
-    vars["ranges"] = has_extensions ? "ranges" : "NULL";
-    vars["range_count"] =
-        has_extensions ? "sizeof(ranges) / sizeof(GPBExtensionRange)" : "0";
-    vars["wireformat"] =
-        descriptor_->options().message_set_wire_format() ? "YES" : "NO";
-
-    if (text_format_decode_data.num_entries() == 0) {
-      printer->Print(
-          vars,
-          "    GPBDescriptor *localDescriptor =\n"
-          "        [GPBDescriptor allocDescriptorForClass:[$classname$ class]\n"
-          "                                     rootClass:[$rootclassname$ class]\n"
-          "                                          file:$rootclassname$_FileDescriptor()\n"
-          "                                        fields:$fields$\n"
-          "                                    fieldCount:$fields_count$\n"
-          "                                        oneofs:$oneofs$\n"
-          "                                    oneofCount:$oneof_count$\n"
-          "                                         enums:$enums$\n"
-          "                                     enumCount:$enum_count$\n"
-          "                                        ranges:$ranges$\n"
-          "                                    rangeCount:$range_count$\n"
-          "                                   storageSize:sizeof($classname$__storage_)\n"
-          "                                    wireFormat:$wireformat$];\n");
+    if (has_fields) {
+      vars["fields_count"] =
+          "(uint32_t)(sizeof(fields) / sizeof(" + field_description_type + "))";
    } else {
-      vars["extraTextFormatInfo"] = CEscape(text_format_decode_data.Data());
+      vars["fields_count"] = "0";
+    }
+
+    std::vector<string> init_flags;
+    if (need_defaults) {
+      init_flags.push_back("GPBDescriptorInitializationFlag_FieldsWithDefault");
+    }
+    if (descriptor_->options().message_set_wire_format()) {
+      init_flags.push_back("GPBDescriptorInitializationFlag_WireFormat");
+    }
+    vars["init_flags"] = BuildFlagsString(init_flags);
+
+    printer->Print(
+        vars,
+        "    GPBDescriptor *localDescriptor =\n"
+        "        [GPBDescriptor allocDescriptorForClass:[$classname$ class]\n"
+        "                                     rootClass:[$rootclassname$ class]\n"
+        "                                          file:$rootclassname$_FileDescriptor()\n"
+        "                                        fields:$fields$\n"
+        "                                    fieldCount:$fields_count$\n"
+        "                                   storageSize:sizeof($classname$__storage_)\n"
+        "                                         flags:$init_flags$];\n");
+    if (oneof_generators_.size() != 0) {
      printer->Print(
-          vars,
-          "#if GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n"
-          "    const char *extraTextFormatInfo = NULL;\n"
-          "#else\n"
-          "    static const char *extraTextFormatInfo = \"$extraTextFormatInfo$\";\n"
-          "#endif  // GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n"
-          "    GPBDescriptor *localDescriptor =\n"
-          "        [GPBDescriptor allocDescriptorForClass:[$classname$ class]\n"
-          "                                     rootClass:[$rootclassname$ class]\n"
-          "                                          file:$rootclassname$_FileDescriptor()\n"
-          "                                        fields:$fields$\n"
-          "                                    fieldCount:$fields_count$\n"
-          "                                        oneofs:$oneofs$\n"
-          "                                    oneofCount:$oneof_count$\n"
-          "                                         enums:$enums$\n"
-          "                                     enumCount:$enum_count$\n"
-          "                                        ranges:$ranges$\n"
-          "                                    rangeCount:$range_count$\n"
-          "                                   storageSize:sizeof($classname$__storage_)\n"
-          "                                    wireFormat:$wireformat$\n"
-          "                           extraTextFormatInfo:extraTextFormatInfo];\n");
+          "    static const char *oneofs[] = {\n");
+      for (vector<OneofGenerator*>::iterator iter = oneof_generators_.begin();
+           iter != oneof_generators_.end(); ++iter) {
+        printer->Print(
+            "      \"$name$\",\n",
+            "name", (*iter)->DescriptorName());
      }
      printer->Print(
-          "    NSAssert(descriptor == nil, @\"Startup recursed!\");\n"
-          "    descriptor = localDescriptor;\n"
-          "  }\n"
-          "  return descriptor;\n"
-          "}\n\n"
-          "@end\n\n");
+          "    };\n"
+          "    [localDescriptor setupOneofs:oneofs\n"
+          "                           count:(uint32_t)(sizeof(oneofs) / sizeof(char*))\n"
+          "                   firstHasIndex:$first_has_index$];\n",
+          "first_has_index", oneof_generators_[0]->HasIndexAsString());
+    }
+    if (text_format_decode_data.num_entries() != 0) {
+      const string text_format_data_str(text_format_decode_data.Data());
+      printer->Print(
+          "#if !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n"
+          "    static const char *extraTextFormatInfo =");
+      static const int kBytesPerLine = 40;  // allow for escaping
+      for (int i = 0; i < text_format_data_str.size(); i += kBytesPerLine) {
+        printer->Print(
+            "\n        \"$data$\"",
+            "data", EscapeTrigraphs(
+                CEscape(text_format_data_str.substr(i, kBytesPerLine))));
+      }
+      printer->Print(
+          ";\n"
+          "    [localDescriptor setupExtraTextInfo:extraTextFormatInfo];\n"
+          "#endif  // !GPBOBJC_SKIP_MESSAGE_TEXTFORMAT_EXTRAS\n");
+    }
+    if (sorted_extensions.size() != 0) {
+      printer->Print(
+          "    static const GPBExtensionRange ranges[] = {\n");
+      for (int i = 0; i < sorted_extensions.size(); i++) {
+        printer->Print("      { .start = $start$, .end = $end$ },\n",
+                       "start", SimpleItoa(sorted_extensions[i]->start),
+                       "end", SimpleItoa(sorted_extensions[i]->end));
+      }
+      printer->Print(
+          "    };\n"
+          "    [localDescriptor setupExtensionRanges:ranges\n"
+          "                                    count:(uint32_t)(sizeof(ranges) / sizeof(GPBExtensionRange))];\n");
+    }
+    printer->Print(
+        "    NSAssert(descriptor == nil, @\"Startup recursed!\");\n"
+        "    descriptor = localDescriptor;\n"
+        "  }\n"
+        "  return descriptor;\n"
+        "}\n\n"
+        "@end\n\n");

    for (int i = 0; i < descriptor_->field_count(); i++) {
      field_generators_.get(descriptor_->field(i))
--- a/src/google/protobuf/compiler/objectivec/objectivec_oneof.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_oneof.cc
@ -120,17 +120,16 @@ void OneofGenerator::GenerateClearFunctionImplementation(io::Printer* printer) {
      "void $owning_message_class$_Clear$capitalized_name$OneOfCase($owning_message_class$ *message) {\n"
      "  GPBDescriptor *descriptor = [message descriptor];\n"
      "  GPBOneofDescriptor *oneof = descriptor->oneofs_[$raw_index$];\n"
-      "  GPBMaybeClearOneof(message, oneof, 0);\n"
+      "  GPBMaybeClearOneof(message, oneof, $index$, 0);\n"
      "}\n");
 }

-void OneofGenerator::GenerateDescription(io::Printer* printer) {
-  printer->Print(
-      variables_,
-      "{\n"
-      "  .name = \"$name$\",\n"
-      "  .index = $index$,\n"
-      "},\n");
+string OneofGenerator::DescriptorName(void) const {
+  return variables_.find("name")->second;
+}
+
+string OneofGenerator::HasIndexAsString(void) const {
+  return variables_.find("index")->second;
 }

 }  // namespace objectivec
--- a/src/google/protobuf/compiler/objectivec/objectivec_oneof.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_oneof.h
@ -61,7 +61,9 @@ class OneofGenerator {

  void GeneratePropertyImplementation(io::Printer* printer);
  void GenerateClearFunctionImplementation(io::Printer* printer);
-  void GenerateDescription(io::Printer* printer);
+
+  string DescriptorName(void) const;
+  string HasIndexAsString(void) const;

 private:
  const OneofDescriptor* descriptor_;
--- a/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.cc
+++ b/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.cc
@ -134,6 +134,32 @@ PrimitiveFieldGenerator::PrimitiveFieldGenerator(

 PrimitiveFieldGenerator::~PrimitiveFieldGenerator() {}

+void PrimitiveFieldGenerator::GenerateFieldStorageDeclaration(
+    io::Printer* printer) const {
+  if (GetObjectiveCType(descriptor_) == OBJECTIVECTYPE_BOOLEAN) {
+    // Nothing, BOOLs are stored in the has bits.
+  } else {
+    SingleFieldGenerator::GenerateFieldStorageDeclaration(printer);
+  }
+}
+
+int PrimitiveFieldGenerator::ExtraRuntimeHasBitsNeeded(void) const {
+  if (GetObjectiveCType(descriptor_) == OBJECTIVECTYPE_BOOLEAN) {
+    // Reserve a bit for the storage of the boolean.
+    return 1;
+  }
+  return 0;
+}
+
+void PrimitiveFieldGenerator::SetExtraRuntimeHasBitsBase(int has_base) {
+  if (GetObjectiveCType(descriptor_) == OBJECTIVECTYPE_BOOLEAN) {
+    // Set into the offset the has bit to use for the actual value.
+    variables_["storage_offset_value"] = SimpleItoa(has_base);
+    variables_["storage_offset_comment"] =
+        "  // Stored in _has_storage_ to save space.";
+  }
+}
+
 PrimitiveObjFieldGenerator::PrimitiveObjFieldGenerator(
    const FieldDescriptor* descriptor, const Options& options)
    : ObjCObjFieldGenerator(descriptor, options) {
--- a/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.h
+++ b/src/google/protobuf/compiler/objectivec/objectivec_primitive_field.h
@ -49,6 +49,11 @@ class PrimitiveFieldGenerator : public SingleFieldGenerator {
                          const Options& options);
  virtual ~PrimitiveFieldGenerator();

+  virtual void GenerateFieldStorageDeclaration(io::Printer* printer) const;
+
+  virtual int ExtraRuntimeHasBitsNeeded(void) const;
+  virtual void SetExtraRuntimeHasBitsBase(int index_base);
+
 private:
  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(PrimitiveFieldGenerator);
 };